The study aims to clarify the abundance and deficiency of available trace elements in cultivated soil systematically in the study region, and explore the correlation between trace elements and their influencing factors, in order to provide a scientific basis for soil testing for formula fertilization, and improve fertilizer utilization rate and soil fertility in Pingliang City. The authors used Cu, Zn, Fe, Mn, B, Mo and S as the main research objects, and evaluated the abundance and deficiency of available trace elements in cultivated soil in Pingliang City. The correlation analysis and regression analysis of trace elements and their influencing factors were conducted by statistical method. The statistical results showed that the average content of available Cu, Zn, Fe, Mn, B, Mo and S was 1.04, 0.92, 13.18, 11.03, 0.51, 0.11 and 15.11 mg/kg, respectively. The content of available S had strong spatial variation, while the content of other elements were moderately variable. The results showed that the abundance and deficiency level of available Cu and Zn in cultivated soil in different regions were from low to medium, that of available Fe and Mn were from low to high, that of available Mo was from relatively low to low, and that of available B and S were from very low to relatively low. The content of available Cu in different soil types was from low to medium, that of available Zn, Fe and Mn were from low to high, that of available B was from relatively low to low, that of available Mo was from relatively low to medium, and that of available S was extremely low. There were certain correlations among soil pH, organic matter and available trace elements. In general, the cultivated soil in Pingliang City was deficient in available B, Mo and S, and available S was extremely deficient. Meanwhile, the available Cu, Zn, Fe and Mn were generally above moderate level. Therefore, according to the evaluation results and the correlation characteristics of soil pH, organic matter and available trace elements, it is suggested to take measures such as reasonable application of organic fertilizer, appropriate adjustment of soil pH, appropriate supplementation of B and Mo fertilizers according to local conditions, more application of S fertilizer, and carrying out experiments and demonstration of trace element fertilizer efficiency, to achieve the high-yield and high-quality crop production and ensure food security.

The study aims to clarify the process of arable land loss caused by loess slope instability, in which the loess slope stability was changed by irrigation water infiltration into soil and loess under large-scale agricultural irrigation. On the basis of statistical analysis of the loss area of arable land, the farmland area under irrigation, the number of geological disasters and the proportion of farmland loss caused by geological disasters in Tianshui of Gansu, the author collected samples of undisturbed soil and loess from typical stratigraphic sections, and tested the physical and mechanical properties and shear strength of soil under natural condition and irrigation. The slope stability was quantitatively analyzed by Swedish method based on limit equilibrium method in combination with Lizheng rock slope stability analysis system. The results showed that the slope was steady and its stability coefficient was 1.074 under natural condition, but under agricultural irrigation, with the increase of water infiltration depth, the stability coefficient decreased gradually, and the slope became unsteady. If farmland irrigation only saturated the soil layer, it would have little effect on the stability of the slope. When the thickness of loess saturated layer was greater than 2 m due to continuous irrigation water infiltration, the slope stability would be reduced by one level and became unsteady. When the thickness of loess saturated layer was greater than 10 m, the slope would be unsteady and landslides would develop, causing arable land loss.

The soil fertility of cultivated land in Gaomi City of Shandong Province was investigated and the spatial distribution of soil fertility was clarified. Eight soil fertility indexes, including soil pH, organic matter, total nitrogen, total phosphorus, total potassium, alkali-hydrolyzed nitrogen, available phosphorus and available potassium, were acquired by gridded sampling and analysis of surface soil. The membership value of each index was determined by the membership function model of fuzzy mathematics, and the weight of each index was determined by principal component analysis. The integrated soil fertility index was calculated using membership value and weight, and then interpolated for mapping. The results showed that the soil in the study area was mainly alkaline, accounting for 37.77% of the total samples, followed by neutral, accounting for 29.52% of the total samples. Organic matter, alkali-hydrolyzed nitrogen and available potassium were mainly insufficient, total nitrogen and total potassium were mainly medium, and total phosphorus and available phosphorus were mainly rich. The membership value of organic matter and total nitrogen were significantly lower than that of other indexes, showing they were the main limiting factors of cultivated land soil fertility. Total nitrogen had the maximum weight value and contributed the most to soil fertility. Alkali-hydrolyzed nitrogen had the minimum weight value and contributed the least to soil fertility. In the study area, the spatial distribution of integrated soil fertility index of cultivated land was mainly medium.

The study aims to comprehensively and timely grasp the cultivated land quality grade, nutrient spatial distribution characteristics and nutrient content difference of different soil types in Pingchuan District of Baiyin City, Gansu Province, and provide an effective basis for rational planting and fertilization in the future. According to the national standard of Cultivated Land Quality Grade, the cultivated land resource management information system at county scale was used to analyze the cultivated land quality grade, nutrient spatial distribution and nutrient content difference of different soil types in Pingchuan. The results showed that the cultivated land quality in Pingchuan belonged to grade five to ten, without cultivated land of grade one, two, three and four. The cultivated land of grade seven had an area of 13543.35 hm², accounting for 34.51% of the total cultivated land area in Pingchuan. The overall nutrient level of the cultivated land in Pingchuan was low, and the cultivated land with low soil organic matter content and total nitrogen content showed a bipolar distribution. The cultivated land with low content of available phosphorus was concentrated, and the cultivated land distribution of other grades was scattered. The cultivated land with high available potassium content was concentrated in the villages and towns in southern Pingchuan; and the nutrient contents of deep cultivated lime-calcium soil were overall high among the six soil types in Pingchuan, and the coefficient of variation was the lowest.

To provide reference and guidance for follow-up management of newly-increased farmland, soil fertility status of newly-increased farmland following land consolidation project in Heyang County of Shaanxi Province, which was part of the eastern Weibei dryland, was studied. Development of soil organic matter, total nitrogen, available phosphorus and available potassium in newly-increased farmland from 12 towns in Heyang County were analyzed and then evaluated comprehensively using the matter-element model. The results show that the soil nutrient concentration is generally low in newly-increased farmland in Heyang County with an average organic matter content of 8.66 g/kg, total nitrogen of 1.30 g/kg, available phosphorus of 18.66 mg/kg, and available potassium of 151.21 mg/kg. The content of soil organic matter is relatively low, the contents of total nitrogen and available phosphorus are moderate, and available potassium is abundant. According to nutrient evaluation grades, soil classified as Grade IV with extremely low fertility accounts for 83.4% of all the newly-increased farmland and has huge room for soil fertility improvement. Taking local economic level and typical nutrient management practices into consideration, the priority should be given to organic fertilizers while application of chemical fertilizers should be increased at an appropriate rate. With respect to cropping systems, a 3-year grain-legume rotation with 1-year of soybean and 2-year of wheat is recommended.

Newly cultivated red soil has many defects, such as strong acid and poor nutrient content, and needs to be improved by many measures. To understand the effect of phosphogypsum and limestone powder on reducing acidity and increasing mineral nutrients in the newly cultivated red soil, a pot experiment was designed to study the effect of applying different amounts and combinations of phosphogypsum and limestone powder on soil acidity, available nutrients and crop growth. The results showed that both phosphogypsum and limestone powder could significantly reduce soil acidity and increase soil available calcium, and the effect increased with the increasing dosage of amendments. Under the condition of equal mass application of the amendments, the effect of the single application of limestone powder or the combined application of phosphogypsum and limestone powder on the reduction of soil acidity was higher than that of the single application of phosphogypsum. The effects of the combined application of phosphogypsum and limestone powder or single application of phosphogypsum on the improvement of soil mineral nutrients, physical properties and vegetable growth were higher than those of single application of limestone powder. Under the experimental condition, the application of phosphogypsum did not significantly increase the accumulation of heavy metals in the soil, and the content of Cd, Cr and Pb in vegetables decreased due to the increase of soil pH, but the content of As increased slightly, which had no obvious effect on the accumulation of other heavy metals in vegetables. The results showed that the newly cultivated red soil with obvious acidification and low nutrients could be improved by the combined application of phosphogypsum and limestone powder instead of limestone powder alone, but the application amount of phosphogypsum should be controlled properly.

To clarify the types of farmland soil texture and texture configuration in Hefei, understand their spatial distribution characteristics in different soil types and administrative regions, and further improve the texture and quality of farmland, based on the data of cultivated land quality monitoring points in Hefei from 2018 to 2020, and combined with Soil Records of each county and district, the spatial characteristics of farmland soil texture and texture configuration in Hefei were analyzed with the support of ArcMap 10.6 software. The results showed that: (1) the cultivated land topsoil texture in Hefei was mainly medium loam soil and heavy loam soil, Chaohu City and Lujiang County had mainly heavy loam soil texture, Feidong County and Feixi County had mainly medium loam soil texture, and the cultivated land topsoil texture was relatively good; (2) the texture configuration of cultivated land in Hefei mainly included upper loose and lower tight type and compact type, the texture configuration of cultivated land in Chaohu City, Feidong County and Feixi County were mainly upper loose and lower tight type, while the texture configuration of cultivated land in Lujiang County and Changfeng County were mainly compact type; (3) to improve the configuration of sandy soil and clayey soil in Hefei, mainly for thin layer type, loose type and upper tight and lower loose type, there are five methods: foreign soil improvement method, organic material backfilling method, mechanical soil improvement method, flood diversion and diffuse siltation method and soil profile reconstruction method. In general, most farmland soils in Hefei are sticky and have good texture configuration ventilation. Targeted improvement measures should be taken for poor texture configuration soils such as sandy clayey soil, so as to improve soil fertility and the quality of cultivated land.

To provide a theoretical basis and technical support for the remediation of Cd contaminated farmland, the effects of Amaranthus hypochondriacus on the remediation of Cd contaminated farmland were evaluated. The effects of the planting modes of Amaranthus hypochondriacus, as well as the effects of the type, filling amount and filling time of chelating agents on the remediation of Cd contaminated farmland were investigated through field trials. The results showed that based on the analysis of Cd extraction efficiency, the labor cost of planting management, and potential environmental risks of Amaranthus hypochondriacus, the strip sowing mode was better than the direct seeding mode and transplanting mode, and NTA was better than EDDS and citric acid. 85 days after planting Amaranthus hypochondriacus, the remediation efficiency was the best under the application of 450 kg/hm² NTA. The extraction efficiency of Cd in the aboveground part and underground part of Amaranthus hypochondriacus was 5.4% and 1.2%, respectively. The extraction efficiency of Cd was 6.6% under single-cropping, the relative improvement rate was 40.5%, and the total extraction efficiency was 13.2%. Therefore, the application of biodegradable chelating agent of NTA could effectively improve the remediation efficiency of Cd contaminated farmland by Amaranthus hypochondriacus, and the technology of Amaranthus hypochondriacus enhanced by NTA is a green, economical, efficient and environmental-friendly remediation method for Cd contaminated farmland, which has a broad application prospect.

Reasonably guiding farmers to adopt technologies that can improve the quality of cultivated land is very important to increase soil fertility, improve soil health, and promote high yield and efficiency of crops. This study analyzed the factors influencing the improvement of cultivated land quality, reviewed the improving technologies, including straw returning, green manure planting, deep ploughing and subsoiling, organic fertilizer applying, formula fertilization by soil testing, lateral deep fertilization for rice, soil conditioner applying and water-fertilizer integrating, and summarized the advantages and disadvantages of these technologies and their applied measures. At present, the research mainly focuses on the integrated application of the technologies for improving cultivated land quality, the differences of farmers’ adoption of various technologies, and the industrial application of modern information technology platform and equipment. It is proposed that we should improve the formulation of standards for multi-function technologies, strengthen the information technology such as high-scoring remote sensing to monitor and evaluate the quality of cultivated land, boost the utilization efficiency of cultivated land resources and perfect the ecological compensation mechanism for farmers.

The objective of this study is to investigate the nutrient resource of animal manure and its environmental pollution risks in Shaanxi Province. This paper estimated the time variation, regional distribution and cropland load of animal manure amount based on the provincial statistical data from yearbook and relevant literature. The environmental risk of animal manure pollution was systematically analyzed. From 2009 to 2017, the amount of animal manure in the whole province presented a trend of first increase and then decrease, with the animal manure amount and nutrients’ amount of 7118.36 × 10⁴ t and 86.76 × 10⁴ t respectively in 2014, being the maximum amount of all the years. Livestock and poultry had geographical characteristics, e.g., sheep, cattle and pigs were the main breeding in northern Shaanxi, Guanzhong and southern Shaanxi, respectively. The animal manure load in the province was 22.36 t/hm², while the nutrient load of nitrogen, phosphorus and potassium was 111.59, 58.56 and 104.22 kg/hm², respectively. The total nutrients’ amount of animal manure was about 35.63% of the amount of agricultural chemical fertilizer. The amount of animal manure in Shaanxi Province is within the allowable range of environmental carrying capacity. The risk of environmental pollution exists in Yangling Demonstration Zone, Ankang City, Hanzhong City, Xianyang City and Baoji City. The nutrient resource of animal manure has great potential to replace chemical fertilizer in Yulin City, Yangling Demonstration Zone, Ankang City, Shangluo City and Hanzhong City, while the rational use of the resource can effectively promote zero growth in chemical fertilizer use.

The management of soil acidification of cultivated land is an important measure to improve farmland quality and ensure food security. Taking Guangdong Province as an example, this paper systematically analyzed the current situation, temporal and spatial evolution characteristics and management modes of soil acidification of cultivated land in Guangdong Province. By using the methods of field investigation, analytic hierarchy process and expert consultation, the study concludes that there are some difficulties in the management of soil acidification of cultivated land in Guangdong, such as insufficient standards, management modes, policy cohesion and funds. The study puts forward suggestions on building management path of soil acidification of cultivated land in Guangdong based on developing standards and specifications, model exploration, policy incentive, public participation and the establishment of long-term mechanism, in order to ensure food security.

Guiding the layout of monitoring sites using basic data has become a research hotspot in recent years. Taking the monitoring of heavy metal Cd pollution in Shunyi District of Beijing as an example, monitoring site layout method for heavy metal pollution of cultivated soil under different data scenarios was developed in this study. Firstly, the basic data scenarios of heavy metal pollution monitoring in cultivated soil were divided. Secondly, the characteristics and applicable data situations of the monitoring site layout method were discussed. Finally, the even variation index and deviation index were adopted to evaluate the uniformity of monitoring sites. The research results showed that: (1) five basic data scenarios were identified based on historical and auxiliary data, namely no historical and auxiliary data, only auxiliary data, only historical data, historical and auxiliary data, and sufficiently historical data; and system/random sampling layout, unbiased sampling layout, encrypted sampling layout, encrypted/unbiased sampling layout and data refinement layout strategies were correspondingly recommended; (2) no historical and auxiliary data were in the western Shunyi District and the corresponding system sampling layout was adopted, while sufficiently historical data were in the eastern Shunyi District and the corresponding data refinement layout was used. Moreover, the even variation index of Shunyi District decreased from 0.546 to 0.490, especially to 0.468 in the eastern Shunyi District, and the deviation index was smaller than the original sampling site layout. It is confirmed that the monitoring site layout method for heavy metal pollution of cultivated soil under different data scenarios has operability and feasibility. This study can provide a theoretical basis and technical support for the sampling site layout method of heavy metal pollution monitoring in cultivated soil.

The key to the operation of the cultivated land rotation and fallow system is to solve the problem of rotation and fallow subsidy. China’s crop rotation and fallow mechanism started late, and its development is not yet perfect. In terms of crop rotation and fallow subsidy, there are problems such as the lack of legal system protection, the single source of subsidy funds, the unclear subsidy target, the difficulty of determining subsidy standards, and the lack of effective supervision of the use of subsidy funds. In order to ensure further advancement of the pilot cultivated land rotation and fallow, this research proposes to improve the legal guarantee mechanism of rotation and fallow subsidy, actively broaden the sources of subsidy funds, clarify the subsidy targets, formulate reasonable subsidy standards, strengthen the supervision of the use of subsidy funds and so on.

Cultivated land is one of the major natural resources of agricultural production development. Cultivated land fertility is a main index in the characterization of farmland quality, and it has direct impact on the development of agricultural production. The construction of cultivated land fertility evaluation index system is the key to ensure the rational utilization of farmland, which is of great significance to the protection of cultivated land, the improvement of soil fertility and the development of agricultural production. In this paper, the relevant research of cultivated land fertility assessment at home and abroad was briefly introduced. Furthermore, the development history, advantages and disadvantages of eight major technologies and methods widely used in cultivated land fertility assessment at home and abroad were summarized. The available research results show that the traditional evaluation methods have some limitations, and the laws and regulations need to be improved. With the rapid development of computer network technology and GIS technology, artificial intelligence method and GIS-based data mining method will gradually become the research hotspot, and the application of GIS and satellite remote sensing technology will be more extensive and could improve the accuracy and timeliness of farmland information. Based on the review conducted by this study, it is expected to provide theoretical and technical support for the Third National Soil Survey, as well as the development of profitable, ecological and sustainable agriculture.

To increase crop yield, farmers' income and utilization efficiency of newly-cultivated land, the authors carried out fertilization experiments in Hedong District of Linyi City in Shandong Province from 2018 to 2020 by integrating soil testing for formulated fertilization, organic fertilizer application, controlled-release fertilization and straw returning. The results showed that the soil nutrient content with different fertilization measures increased in varying degrees in 2020, and the largest increasing rate was found under organic fertilizer application and straw returning. And compared with conventional fertilization, soil testing for formulated fertilization, organic fertilizer application and straw returning all had higher yield and income. However, considering the cost of organic fertilizer application and straw returning, the combination of formulated fertilization with straw returning is the best for improving the nutrient content of newly-cultivated land and increasing farmers' income.

The temporal-spatial changes of construction land and arable land and the impact of construction land expansion on arable land in Changchun were studied to provide reference for rational use of land and protection of arable land in the black soil region. Land use information of the study area in 2005 and 2019 were extracted from Landsat TM/OLI remote sensing images using the object-oriented-decision tree classification method. Then the temporal-spatial changes of construction land and arable land and the impact of construction land on arable land in the aspect of quantity, quality and structure were studied. The results showed that the area of construction land had expanded by 21163.30 hm² since 2005, while the area of arable land had decreased by 19011.81 hm². Newly added construction land occupied 18170.84 hm² of arable land, accounting for 85.33% of the total area of the increased construction land. The expansion of construction land also led to an increase in the degree of fragmentation of arable land; most of the arable land occupied by construction land was originally high-quality arable land and the proportion of the area of Grade I to III could reach 72.17%. The research results are of great significance for coordinating the protection of arable land resources in rapid urbanization in the black soil region.

The study aims to provide reference for the cultivated land quality evaluation and acceptance inspection of newly constructed high-standard farmland. According to the standard of Cultivated Land Quality Grade (GB/T 33469—2016), this paper evaluated the cultivated land quality grade of the newly constructed high-standard farmland by ArcGIS in Guoyang County, Anhui Province. It also analyzed the change of cultivated land quality grade before and after the construction and the improvement degree of the evaluation indexes. The results showed that the average cultivated land quality grade was 3.17 for the newly constructed high-standard farmland in Guoyang, which was increased by 1.07 grade compared with that of before the construction in 2019. The area of high-yield farmland in the project area increased significantly from 439.94 hm ² to 1653.14 hm²; the area of middle-yield farmland decreased significantly from 2283.65 hm² to 1144.87 hm². Through the analysis of subsoiling and land levelling, irrigation and drainage projects, and the shelterbelt projects in the construction of high-standard farmland, this study discussed the effect mechanism of high-standard farmland construction on the evaluation indexes of plough layer thickness, texture of plough layer, irrigation and drainage benefits, farmland windbreak network, obstacle factors and so on.

Strictly controlled farmland refers to the cultivated land with heavy metals’ contents (cadmium, mercury, arsenic, lead and chromium) exceeding the risk control standard specified by Soil Environmental Quality Agricultural Land Risk Control Standards (GB15618-2018). This article evaluated the safety of planting edible crops in strictly controlled farmland, aiming to provide reference for cultivation structure adjustment in strictly controlled farmland, as well as the safe use of contaminated farmland. Present research indicates that the heavy metals in the seeds easily exceed the standards when oil crops, such as rape, peanut, sesame and sunflower, are cultivated in strictly controlled farmland, while heavy metals’ (such as As and Pb) contents in vegetable oil are lower than the safety limits, and the oil is safe for diet. But for Camellia oleifera seed oil, the excessive rate of heavy metals is relatively high, so it is necessary to further evaluate the heavy metals’ accumulation characteristics of Camellia oleifera varieties, and the safety of Camellia oleifera seed oil. Seed meals could be used as animal feeds and organic fertilizers after the removal of heavy metals, which could maximize the utilization of resources. Nevertheless, there is a risk of excessive heavy metals in maize silage cultivated in strictly controlled farmland, while the risk in maize grains is relatively low, and the low heavy metal accumulation maize varieties could be further screened to achieve the purpose of safe production of grains. The safety of heavy metals in tea should be further studied in strictly controlled farmland. Furthermore, it is necessary to improve the standard system of heavy metal safety limits of edible crops, strengthen the research and development of straw treatment and resource utilization technologies, and establish an ecological compensation mechanism of specific crop straw recycling in strictly controlled farmland.

As the carrier of plant growth, cultivated land is an important means of agricultural production. With the progress of the society, the role of cultivated land quality becomes increasingly prominent. Improving the quality of cultivated land is of great significance to enhance the cultivated land productivity and ensure the national food security. Based on previous studies, this paper summarized the definition of cultivated land quality, which could be understood as the comprehensive productivity of cultivated land under the combined action of cultivated land environment, cultivated land soil property, cultivated land management level and other factors. Soil property of cultivated land is the most intuitive expression of cultivated land quality and has been the focus of the research. In this paper, soil properties such as soil type, soil texture, soil fertility and plough layer structure were selected as major indexes, and their effects on cultivated land productivity were summarized. At present, the research on cultivated land quality is in the preliminary stage, and a comprehensive and systematic research should be the direction in the future.

To understand the role of clay mineral amendments in improving the soil fertility of newly reclaimed farmland, four clay minerals, bentonite, kaolinite, zeolite and diatomite, were selected for testing their effects on mineralization of organic fertilizers and accumulation of soil organic carbon by incubation experiments with 10% addition of the amendments. The results showed that the addition of clay minerals could significantly increase the accumulation of soil organic carbon as compared with the control, and the effect decreased in the order of bentonite> kaolinite> diatomite> zeolite. Aggregate measurement and heavy liquid fractionation showed that the addition of clay minerals could significantly increase the amount of water-stable aggregates in the soils and promote the formation of mineral-bound organic carbon. In general, clay minerals could increase the stability of organic carbon, which is the main reason for increasing organic carbon accumulation in the soils.

To continuously build the internal quality of cultivated land, improve its comprehensive production capacity, explore the productive potential and the yield increasing potential of crops, and provide reference for the structural adjustment of planting industry, this paper took Wuxiang County of Shanxi Province as an example to optimize the layout of planting industry. Firstly, the distribution of cultivated land quality in Wuxiang County was analyzed, including the general situation of cultivated land resources, the quality grade of cultivated land and the topographic condition in each township. Then the change of the year-on-year growth of crop yield per unit area in Wuxiang County from 2015 to 2019 was examined. The comprehensive comparative advantage index method was used to calculate and study the production scale advantage index, production efficiency advantage index and comprehensive comparative advantage index of millet, corn, sorghum, soybean, potato, vegetable, oil plants, medicinal materials, jujube, watermelon, walnut and apricot in comparison with same crops in other parts of China. Finally, by making full use of the production conditions of cultivated land quality in different regions of Wuxiang County and the calculation results of the comparative advantage of millet, corn, sorghum, potato, medicinal materials, apricot and walnut in the whole country, the layout strategy was adjusted. Three major planting industry layouts were worked out for Wuxiang County, namely, “the efficient and comprehensive cluster area, the characteristic and quality demonstration area and the development and protection area”, thus to establish the high quality and high efficiency planting industry base and cluster. By transforming the advantage of cultivated land quality and the comparative advantage of crops into economic advantage, the optimum planting pattern of “expanding the scale advantage, ensuring the yield advantage and strengthening the quality advantage” was constructed to improve the grain yield, highlight the characteristic varieties, and increase the agricultural income.

To find out the spatial distribution characteristics and influencing factors of exchangeable magnesium content in cultivated soil in Sanming City, based on the test results and related data of 4833 soil samples, the spatial distribution characteristics and influencing factors of exchangeable magnesium content in cultivated land soil in Sanming City were analyzed by statistical and geographical statistical methods. The results showed that the exchangeable magnesium average content of cultivated land soil samples in Sanming City was at medium level, and the average value was 62.7 mg/kg. The difference of exchangeable magnesium average content in soil samples from different counties (cities or districts) reached significant level. The proportion of samples with deficiency exchangeable magnesium content and arable land with deficiency exchangeable magnesium content accounted for 44.15% and 40.72%, respectively. Except that the difference of exchangeable magnesium content by soil type grouping was not significant, the differences of the soil exchangeable magnesium content by the other influencing factors grouping were significant. Therefore, applying organic fertilizer, adjusting soil pH, improving sandy soil texture and supplementing magnesium fertilizer could be the main measures to control soil exchangeable magnesium content in Sanming City.

This study took the cultivated land area of 181 counties in Sichuan Province from 1999 to 2018 as the research object, based on principal component analysis and spatial analysis, described the spatial-temporal pattern evolution characteristics of cultivated land area in the province and explored the main driving factors. The results showed that from 1999 to 2018, the total cultivated land area in Sichuan had five stages: continuous decrease, slow increase, fluctuating change, rapid increase and stable change. In the whole process of change, the spatial change of cultivated land in the province mainly occurred in northwest Sichuan plateau and Chengdu plain. Among them, the cultivated land area of southwest Sichuan mountainous area and northwest Sichuan plateau increased, while the cultivated land area of central Sichuan hilly area, Chengdu plain area and mountainous area around basin decreased. The gravity center of cultivated land area moved southward obviously. The main driving forces of cultivated land change in Sichuan included agricultural development foundation, economic development level and geographical location. Among them, solid foundation of agricultural development was the main reason for the increase of cultivated land in northwest Sichuan plateau. The level of regional economic development and location characteristics were positively driving the change of cultivated land in the mountainous areas around the basin. The level of regional economic development is the negative driving force of the change of cultivated land in hilly area of central Sichuan. The interaction of the negative effect of economic development level and the positive effect of agricultural development foundation and location advantage resulted in the cultivated land change in Chengdu plain and southwest Sichuan mountainous area. The above conclusions could provide a scientific basis for making reasonable policies on land use and cultivated land protection in Sichuan Province.

The fragmentation of cultivated land is the main problem in realizing large-scale management of agriculture in China. Based on the data of rural contracted land management right in Heshun County, this paper used landscape pattern software to obtain three indexes: patch area index (PAI), patch shape index (PSI) and patch density index (PDI), to measure the degree of cultivated land fragmentation. Beside, GIS spatial analysis and regression analysis were used to study the fragmentation of cultivated land and its influencing factors. The results demonstrated that: (1) patch area index (PAI), patch shape index (PSI) and patch density index (PDI) had the same spatial distribution characteristics, namely, the fragmentation of cultivated land in eastern, western and central regions showed a downward trend in turn; (2) the cultivated land fragmentation showed spatial aggregation, in the local spatial autocorrelation analysis, L-L type was concentrated around the central county seat; (3) in view of the influencing factors, the per capita cultivated land area had a significant effect on the patch area index and patch density index, while the slope and homestead rate had a negative effect on the patch area index and the patch density index, and the labor force ratio and per capita cultivated land area had a negative effect on the shape index. This research can provide scientific reference for improving the utilization rate of regional cultivated land and realizing agricultural scale management.

To understand the evolution law of soil fertility of red soil reclamation land in low hilly area, we studied the soil quality evolution in the process of reclamation, fertilization and maturation from red soil farmland by the method of replacing time with space. The results showed that: the contents of soil organic matter, total nitrogen, water-stable aggregates, available phosphorus and available potassium decreased significantly at the initial stage of reclamation of wasteland red soil because of the mixing of topsoil and subsoil, but with the increase of fertilization and maturation time, the soil acidity decreased gradually, the base saturation, the organic matter and the ratio of humus to organic matter increased; meanwhile, the contents of water-stable aggregates, total phosphorus, available phosphorus and microbial biomass carbon gradually increased, the soil texture gradually became lighter, and the C/N ratio gradually tended to be stable. Based on the comparative study of the soil fertility and productivity of reclamation cultivated land in different places and at different reclamation times, the following indicators are put forward for soil maturation of reclamation cultivated land in red soil hilly area: the thickness of tillage layer is >15 cm; the structure mainly dominated by small block and cluster; the percentage of >0.25 mm water stable aggregates is >30%; the soil pH value is >5.5 the base saturation is >60%; the soil organic matter content ranges from 15 to 20 g/kg with C/N ratio of 12-17, H/F is >0.40, and the ratio of humic acid and organic matter is >0.30; the soil available phosphorus, available potassium, and microbial biomass carbon are 7.5-30 mg/kg, >75 mg/kg, >75 mg/kg, respectively.

The erosion gully has caused a large amount of soil loss on the sloping farmland in the black soil area of northeast China. Research on the erosion gullies on the sloping farmland in the black soil area is of great significance for soil erosion control, farmland protection and ecological restoration. At present, relevant researches had been carried out on the influencing factors, prediction and prevention measures of the occurrence and development of erosion gullies on slope farmland in black soil area. This article conducted an in-depth discussion on the current research, and pointed out that the current classification of erosion gullies in black soil areas lacked detailed standard classification basis, and the research on the influence factors was not comprehensive enough, and there was a lack of effective quantitative evaluation on the economic and ecological benefits of erosion ditch management and the effect differences of various treatment measures. In view of the existing research deficiencies, the study proposed that future research should be focused on standardizing the classification and grading system of erosion gullies in the black soil area, the influence of factors such as soil, plants, engineering measures and farming measures on the erosion gullies, and the quantitative evaluation of the effects of erosion gully control measures.

Constructing an efficient and standardized spatial interpolation method is an important issue for building the big data platform for cultivated land quality and serving macroscopic decision-making, and is conducive to quickly and accurately obtain the distribution map of cultivated land quality indicators of counties and even the whole country. Through literature and research review, this study summarized the current concept and process of spatial interpolation method, and clarified its precision influencing factors and application status in monitoring and evaluation of cultivated land quality. Combined with the actual application requirements of the big data platform for cultivated land quality, four in-depth research directions were put forward, including regional interpolation, geographic barriers interpolation, auxiliary variables interpolation, and module design of interpolation. The research results could provide method reference for the standardized processing of cultivated land quality data.

To quickly and accurately grasp the spatio-temporal changes of the consolidated farmland’s quality and improve the evaluating efficiency of farmland quality grades, the paper took the reclaimed paddy project area in Muhe Village, Longjie Town, Lianping County as the research area, combined the traditional farmland classification with ModelBuilder modeling method to construct a rapid evaluation framework system of farmland quality grades in the context of reclaimed paddy engineering projects. Based on the updated results of farmland quality grades in Lianping County in 2016, the study completed the ModelBuilder modeling process by combining the information of engineering data, farmland utilization status survey and field soil sampling inspection in the project area. The weighted average and spacing division methods were used to evaluate and compare the farmland quality grades in the study area. The evaluation results showed that the farmland quality grades were significantly improved after the implementation of reclaiming paddy project in the study area. The provincial natural, utilized and economic quality grade of farmland was promoted by an average of 1.31, 0.63 and 0.97, respectively, and the national natural, utilized and economic quality grade of farmland quality was promoted by an average of 1.06, 0.56 and 1.02, respectively. The research showed that ModelBuilder modeling could realize the automatic flow process of complex calculation of farmland quality evaluation for reclaimed paddy fields, and could quickly form the integrated results of charts and graphs. Compared with the traditional algorithm, ModelBuilder modeling has the characteristics of full automation, super-efficiency, high interaction and portability, and could be efficiently applied to the related work of complex farmland quality evaluation in combination with lightweight python programming.

To analyze the quantitative characteristics, spatial distribution and limiting factors of different types of cultivated land in Luohe City, Henan Province, and put forward specific protection measures, a comprehensive evaluation system with 17 selected indexes was constructed. By means of analytic hierarchy process and membership function method, the weight value and membership degree of each index were studied. The authors calculated the comprehensive indexes and grades according to natural breakpoint method. The results showed that: (1) the quality of cultivated land decreased from northeast to southwest in Luohe City, among which the quality of cultivated land in Linying County, Yancheng District, Yuanhui District and most of Zhaoling District was relatively high, and the quality of cultivated land in southwest Wuyang County and northern Zhaoling District was relatively poor; (2) the proportion of superior land, higher land, middle land and lower land in Luohe City was 12.48%, 39.28%, 38.58% and 9.67%, respectively, and the quality level of cultivated land needs to be further improved; (3) according to the main restrictive factors such as soil nutrient status, farmland infrastructure construction and soil barrier factors, the corresponding improvement measures were implemented. This study provides effective references for strengthening cultivated land quality construction and enhancing agricultural production capacity in Luohe City.

Two different types of sand accretion instruments were installed on the abandoned farmland of different years, and the similarities and differences of the two sand accretion instruments were analyzed through a comparative study on the structural characteristics of the wind sand flow, so as to select the ideal sand accretion instruments for the study of wind sand flow under different wind sand environment conditions in arid and desert areas. The results showed that (1) the annual sediment transport of No.2 sand accretion instrument was significantly higher than that of No.1, the higher the wind sand flow, the greater the difference, and the difference had a close relationship with the distance to sand source, the farther distance, the more obvious the difference; (2) there was a significant linear correlation between the annual sediment transport volume of the two sand accretion instruments, and the correlation coefficient was up to 0.998, indicating that there was a significant linear correlation between the amount of wind sand flow collected by the two sand accretion instruments; (3) according to the monthly variation of sediment transport rate of the two kinds of sand accretion instruments, the overall performance was that the sediment transport amount was consistent with the local wind season, and the monthly variation rules between them were also very similar, however, the sediment transport amount of each month still showed that the sand accretion instrument 2 was greater than that of the sand accretion instrument 1; (4) under the same wind speed, the sediment transport rate of the two kinds of sand accretion instruments showed a downward trend with the increase of the number of years of farmland returning, the longer the number of years of farmland returning, the larger the sediment transport rate was, and the larger the change range was within the range of 0-50 cm; while, the shorter the time of farmland returning, the smaller the sediment transport rate was, and the small change range was within the range of 0-50 cm. The results showed that under the same condition, the sand volume collected by sand accretion instruments 2 was 1.7-1.9 times of that collected by sand accretion instrument 1. The two kinds of sand accretion instruments could be used to observe sand flow in areas with large amount of wind-sand, while good results could be obtained when sand accretion instrument 2 was used to observe sand flow in areas with small amount of wind sand.

To understand current situation of farmland resource allocation and the influence of market economy on the slope of Yunnan planned tobacco area, the distribution and difference of slope types in core, high quality and suitable area were analyzed, based on the latest results of flue-cured tobacco planting zoning data and slope grid data. On this basis, combined with the data of rural per capita disposable income of each city, the impact of market economy on the slope of tobacco planting area was analyzed. The results showed that the planned area of flue-cured tobacco accounted for 47.9% of the total area of class Ⅰ and Ⅱ, and accounted for merely 18.7% of the total area of class I to III which was suitable for planting flue-cured tobacco in the whole province. However, 40.0% of the latest planned tobacco fields were in class III farming areas, and 26.3% in class IV and V areas. The percentage of class III to V flue-cured tobacco planning area in each prefecture and city was positively proportional to the per capita disposable income in rural areas, which indicated that the higher the disposable income, the more obvious the tobacco planting area developing to cultivated land with large slope. In general, under the effect of market economy, the development of flue-cured tobacco industry in Yunnan is at disadvantage in the allocation of cultivated land resources.

To study the effect of long-term reducing fertilization on soil nutrient content in protected cultivated land under different cropping systems, the soil nutrients and fertilization rate of five long-term soil nutrient monitoring points in Jinning County of Kunming City were statistically analyzed, and the effect of different fertilization treatments on soil nutrient was compared. The results showed that there was no significant difference in soil organic matter between long-term reducing fertilizer treatment and conventional fertilizer treatment, but the organic matter in long-term non-fertilization decreased significantly. Compared with those of the fertilization treatment, soil available N and available P of non-fertilization treatment decreased obviously. There was no significant difference in soil available N and available P between reducing fertilizer treatment and conventional fertilizer treatment, but available N decreased as nitrogen fertilizer decreased. Due to the long-term phosphorus fertilizer application, enrichment effect of phosphorus was significant in protected soil. Long-term reducing nitrogen application will not result in the decrease of soil organic matter, available N and available P in protected cultivated land.

To study the spatial and temporal dynamic of soil organic matter content of different soil types in Oroqen and the relationships between organic matter content and total N content, the soil organic matter and total nitrogen content of 7722 soil samples collected in Oroqen Banner in 2008-2014 were analyzed and compared with the results of local soil samples taken during The Second National Soil Census in 1986. Furthermore, a pot experiment with different soil organic matter contents was conducted to determine the effects of soil organic content on botanical characteristics, agronomic traits and yield of soybean. The content of soil organic matter and total N were determined by oil bath heating potassium dichromate volumetric method and semi-micro Kjeldahl method, respectively. There were five levels for soil organic matter content (23.24, 41.45, 60.21, 81.37, 98.71 g/kg), and two fertilizing levels (fertilizer application and no fertilizer) in the pot experiment and soybean cultivar ‘Beidou 26’ was used as material. Developmental rate and agronomic traits were investigated at flowering and maturity stage, and yield measurements were taken after harvest. The soil organic matter content of arable layer in Oroqen Banner was significantly decreased by 49.06% from 127.24 to 64.82 g/kg in recent 30 years. The changes of organic matter content in different soil types were analyzed: organic matter content of swamp soil significantly decreased by 59.08% from 165.9 to 67.89 g/kg; organic matter content of dark brown soil significantly decreased by 47.20% from 120.9 to 63.83 g/kg; organic matter content of brown forest soil significantly decreased by 30.44% from 149.2 to 103.79 g/kg; organic matter content of meadow soil significantly decreased by 40.26% from 111.5 to 66.61 g/kg; organic matter content of black soil significantly decreased by 26.01% from 88.7 to 65.63 g/kg. Soil organic matter and total nitrogen content showed an obvious positive correlation. The effects of chemical fertilizer application on soybean seed yield were dependent on the soil organic matter content and no increasing effects were found after the soil organic matter content reached 81.37 g/kg. Soil organic matter in Oroqen Banner decreased by 49.06%, showing that unsustainable farming consumed a lot of soil organic matter. Significant differences of organic matter changes over years were found among the soil types, i.e. swampy soil had the largest decrease, while black soil had the smallest decrease and the dark brown soil was in the middle. Soil rich of organic matter, even without chemical fertilizer application, can also produce a higher yield of soybean. Therefore, enriching the organic matter content is the fundamental measure to improve the soil productivity and agricultural production efficiency. The authors suggest that crop rotation and straw returning are the most important measures for elevating soil organic matter.

To fully understand the effect of different amendments on the physical properties of newly cultivated land, a greenhouse culture experiment was carried out on three kinds of newly cultivated land soil with different texture. The effects of 14 amendments, including polyacrylamide, β-cyclodextrin, potassium fulvic acid, bentonite, kaolin, vermiculite, zeolite, diatomite, limestone powder, commercial organic fertilizer, rice straw, Chinese milk vetch, and biochar and peat, on soil structure, water retention and water permeability of the three kinds of soil were compared. The results showed that most of the amendments could improve the soil water stability aggregates, bulk density, saturated water holding capacity, wilting water content, saturated water conductivity and effective water range. And the effect of applying polyacrylamide, β-cyclodextrin, potassium fulvic acid on the physical properties was the most obvious, while the application of peat and commercial organic fertilizer also had a better effect on the physical properties of the soil. Compared with the control, the water stability aggregates of the soil with the application of polyacrylamide, β-cyclodextrin, potassium fulvic acid increased by 42.88%-299.38%, 41.15%-239.69% and 55.39%-207.70%, respectively. The application of peat and commercial organic fertilizer had better improving effects on the soil of newly reclaimed land in low hilly region, the water stability aggregates increased by 31.90%-119.69% and 35.19%-71.05%, respectively. Bentonite, Chinese milk vetch and rice straw could obviously improve the water stability aggregates of sandy soil and loamy soil. The application of kaolin and vermiculite could obviously improve the water stability aggregates of sandy soil, but they had little effect on the water stability aggregates of clay and loamy soil. Biochar had little effect on the content of water stable aggregates, but it could increase the saturated water holding capacity, saturated hydraulic conductivity and effective water range, and reduce the wilting water content. In general, the organic amendments, such as polyacrylamide, β-cyclodextrin, potassium fulvic acid, peat and commercial organic fertilizer, can effectively improve the overall physical properties of the soil, and are more suitable for being applied to the newly reclaimed land in low hilly regions.

To solve the problem of long-term extensive management of China’s agriculture, and to study the cooperative protection system of cultivated land and ecological civilization in China, the literature research method and inductive deduction method were used to analyze the cooperative system of cultivated land agriculture under the representative of national environmental conservation agriculture in East Asia. The results showed that, Japan’s farmland agricultural environmental protection payment system, ecological compensation market certification system, and farmland legal system guarantees are established based on the principle of ecological compensation and have been tested in practice to effectively improve the market participation and farmers’ independent input. In conclusion, China has made unremitting efforts to promote the rational use of farmland, but still needs to go ahead in fields of setting a fallow system for the coordinated protection of cultivated land ecology, establishing an ecological compensation system based on local conditions, and accelerating the establishment of a special fund for the collaborative protection of farmland ecology.

Fallow system is an effective way to ensure the strategy of storing grain in land and technology, which s great strategic significance to the national food security. This paper summarized the background, specific implementation way and compensation method of the fallow system in United States, Europe and Japan, analyzed the uniqueness of cultivated land in resource-poor areas, destructed cultivated land areas, and weak ecological areas in China, and put forward corresponding improvement measures and fallow subsidy policies. By comparing the fallow models and analyzing the current domestic fallow system, the authors believe that the current domestic system should be enhanced by developing the prediction model, scientifically planning the fallow area, strengthening government supervision, changing current fallow subsidy mode, and motivating more research institutions and commercial companies to join in.

Based on the official data on cultivated land use management projects funded by the National Natural Science Foundation of China from 1999 to 2018, using the methods of quantitative analysis, classified statistics, qualitative and quantitative analysis, this paper makes a comprehensive analysis of the annual situation, project types, project departments, project units and research directions of cultivated land use projects. The results show that: in the 20 years, under the guidance of national policies, the number and amount of cultivated land use management projects are increasing; the types of projects are mainly youth science fund projects, general projects and regional science fund projects; the youth scientific research team is growing, and the scope of project approval units is wide, but most of the projects are concentrated in institutions with strong research strength; the project departments and research directions tend to be diversified. While deeply exploring the traditional mainstream directions, the funding expands the research theme, innovates the research ideas and grasps the new hot spot of the research. According to the analysis, the research content of the fund project is becoming more abundant and the research system is gradually systematic, but the depth and real-time of the research should be strengthened, the protection, the sustainable utilization and the evaluation of cultivated land are the hot spots in recent years, and the related research needs to be improved.

The paper aims to study the soil nutrient status in Hetao Plain and explore the spatial variability and distribution characteristics of soil nutrients at county scale. By taking the arable land in Hangjinhouqi County as the object, the content of soil organic matter, total soil nitrogen, available phosphorus and rapid available potassium in the cultivated soil were studied, the spatial variability and distribution characteristics of soil nutrients were analyzed by field investigation and geostatistics. The results showed that the average content of soil organic matter, total nitrogen, available phosphorus and available potassium in topsoil in the arable layer was 13.90 g/kg, 0.93 g/kg, 16.25 mg/kg and 170.79 mg/kg, respectively. The soil organic matter and total soil nitrogen in the arable layer were in a deficient state, the content of available phosphorus was moderate, and the rapid available potassium was abundant. From the perspective of spatial variation and correlation, the variation degree of soil nutrients was moderate, the organic matter and rapid available potassium were moderately correlated, and the total nitrogen and available phosphorus were weakly correlated. From the perspective of spatial distribution pattern, the soil organic matter came to a trend of high level in the northwest, low level in the southeast and northeast, and the distribution of soil total nitrogen was similar to that of soil organic matter. The overall distribution of available potassium in soil was relatively balanced; the spatial difference of available phosphorus was obvious, showing a pattern of east high and west low. Concerning the soil nutrient content and distribution in the region, the process of nutrient management should be as following: control the nitrogen, stabilize the phosphorus, stabilize the potassium, combine the planning of the whole district with the key response, and adhere to the organic fertilizer, organic and inorganic combined fertilization strategy. The investigation and statistical analysis of soil nutrient status at the county scale clarified the spatial distribution characteristics of regional soil nutrients and their relationship with land using patterns, providing a scientific basis for soil nutrient management, soil fertility and rational fertilization planning in Hetao Plain.

The paper aims to explore the spatial pattern and spatial variation rule of thickness and soil nutrients of the cultivated land in dry farming region. Taking typical cultivated land in Jinzhong basin as the research object, we analyzed the spatial variation of thickness of cultivated layer (TCL) and soil nutrients by geostatistics method, with soil organic matter (SOM), pH value, available phosphorus (AP) and slow-effect potassium (SK) as the soil nutrients indexes. The results showed that: (1) the spatial autocorrelation of each index decreased with the increase of distance; (2) the optimum semivariance model of AP was Gaussian model, and the optimum semivariance model of other indexes was exponential model; the ratio of Nugget to Sill of each index was: SOM>AP>pH>TCL>SK; (3) the spatial pattern of TCL and AP had the tendency of higher in northwest and lower in southeast, SK had the spatial pattern of higher in northeast and lower in southwest, SOM had the spatial pattern of higher in southwest and lower in northeast, the pH value was high in the whole study area except Beiguang. In conclusion, geostatistical method can describe the spatial pattern and variation characteristics of soil properties well; in the spatial variation process of soil properties, the randomness and structure coexist, and the randomness is less than 50%.

【OBJECTIVE】The paper aims to find out the basic situation of the farmland productivity of Pearl River delta plain, the evaluation of the farmland productivity in Zhongshan city of Guangdong province was investigated.【METHOD】Geographic Information System technology(GIS), fuzzy mathematics method, Delphi method, addition-multiplication and the isometric method were employed for the evaluation.【RESULTS】The results showed that the farmland productivity in Zhongshan has generally increased. The area of high-yield farmland accounted for 42.17% of the total farmland area, and the area of middle-yield farmland accounted for 53.72%, while the area of low-yield farmland accounted for only 4.11%. There are obvious regional differences in cultivated land fertility level in different towns. Multiple cropping and double cropping fields were mainly high-yield fields, whilst one cropping fields were mainly middle-yield fields. The middle and low-yield fields mainly included irrigation-improved type, over sandy or sticky type, barren-fertility type and gley-paddy-field type, among which gley-paddy-field type has the largest area.【CONCLUSION】The evaluation results of farmland productivity accorded with the actual situation. It can not only reflect the basic situation of the farmland productivity in Zhongshan city and guide local agricultural production, but also provide a useful exploration for the evaluation of farmland productivity in pearl river delta plain, and help to improve the local farmland productivity.