The black soil area in Northeast China serves as a "ballast" to ensure China's food security. Unreasonable development and utilization lead to serious black soil degradation in some areas and affect regional food production and economic and social development. In the context of the intensification of the contradiction between food supply and demand around the world, we should pay more attention to the overall situation of regional sustainable development, and seek for systematic, scientific, and economic solutions. Guided by the concept of integrated geography, this study establishes a regional all-for-one customization model of black soil granary on the basis of the regional system of human-land relationship, customized and accurate management, agricultural system theory, and agricultural informatization. The aim of this regional all-for-one customization model is to systematically diagnose the key problems and leading factors of black soil degradation and find out a solution that combines the commonness and individuality of black soil protection from the perspective of multi-scale linkage, multi-factor coupling, and multi-technology cooperation. The regional all-for-one customization model of black soil granary integrates the two perspectives of "global" and "customization" into the protection and comprehensive utilization of black soil for the first time. It adopts zoning, grading, and classification as the main strategy and big data and artificial intelligence as the main technical approaches. Relying on the "satellite-air-ground network" three-dimensional monitoring system and combined with the all-for-one customization platform driven by big data and artificial intelligence, the model constructs three strategies of different scales. First, "implementing strategies by regions" are implemented at the regional scale to formulate the regional agricultural resource allocation scheme and agricultural zoning, which can provide strategies to protect and utilize black soil effectively. Second, the "determining strategies according to villages" is implemented at the village scale to formulate the black soil protection and utilization model for different categories of villages, which can promote the organic integration of black soil protection and rural revitalization. Third, the "one strategy for one field" concept is applied at the field scale to provide accurate strategies for soil restoration and yield improvement in a fixed, quantitative, and regular manner. Multi-scale integrated demonstration and scheme verification of the regional all-for-one customization model of black soil granary are conducted in Qiqihar city at three scales, namely, region, village, and field, to solve the key issues in black soil protection and utilization and form a replicable and popularized system solution, thus providing a model for the sustainable development of Chinese and global black soil agriculture. The regional all-for-one customization model of black soil granary has important theoretical and practical value in promoting the high-quality development of regional agriculture and rural revitalization, and it provides a demonstration model of land protection and utilization for the black soil area in China and the whole world.

The Northeast China Plain is an important commercial grain production base of the country, with rice being one of the region's principal food crops. Despite the exceptional quality and fertility of the region's black soil, excessive fertilizer application is nonetheless widespread. As a result, large-scale surveys and soil incubation experiments were conducted in Heilongjiang, Jilin and Liaoning provinces to clarify the spatial pattern, differential characteristics and the reduction potential of rice fertilization in the black soil area. The findings revealed that both netrogen (N) application intensity and economic yield dropped progressively from south to north in the region, with the decrease in N application intensity being greater than that in yield. As a result, N fertilizer partial productivity steadily increased from south to north. Compared to the theoretically suitable N application rate, the theoretical N reduction potential of rice area in Liaoning, central and western Jilin and Heilongjiang were determined to be 16.7%~24.7%, 8.7%~17.8%, and 2.0%~11.4%, respectively. In the three provinces, there is no significant difference in the quantity of accumulative soil mineralization of typical rice soils. Therefore, variances in N application to rice in Heilongjiang, Jilin, and Liaoning are mostly influenced by changes in the N quantity carried by aboveground biomass.

In China, the national spatial planning system is built largely upon prefectural plans, a critical part of which in many prefecture-level cities would be agricultural planning. When we develop such plans for the black soil regions in Northeast China, much effort is needed to guarantee both the black soil conservation and food security, given the rarity and importance of the black soil to agricultural use. In this research, we took Qiqihar as a case to establish an evaluation index system of land space function in the black soil areas that integrated grid-scale and administrative regional-scale. We analyzed the spatio-temporal evolution features of the production-living-ecological space (PLES) in the study area and evaluated their coupling coordination. Based on this analysis, we put forward an optimal strategy for spatial planning regulation to meet the requirement of the diversified regional development and social demands in Qiqihar in the context of prioritizing black soil preservation and food security. The main conclusions can be drawn as follows: regarding the production-life-ecology function, the mildly imbalanced and barely coordinated areas increased from 2010 to 2018, when the production and living space grew to a certain extent. The low coordination of PLES, the regionally varied conflict between different functional spaces, and the potential risks of unsustainable development of black soil resources jointly constituted the conflict arising from its spatial planning. Eventually, we constructed a configuration model for optimizing spatial planning under the constraint of conflict between PLES on multiple scales. It is our suggestion that the enhancement of functional spatial planning at the prefecture level should drive the priority on which the national food security is based, by which the black soil preservation is oriented, and on which the allocation of "human-water-land" resources depends. To achieve such enhancement with the advantages of our prosperous industry, we should wisely channel the advantages of particular regions toward better development, promote the accelerated development of the critical cities and towns, improve the utilization efficiency of black soil resources, and encourage effective land use of towns in harmony with that of counties.

The black soil region of Northeast China is the major food base and one of the most sensitive regions to climate change in China. However, the characteristics of crop phenological response, the integrated impact of climatic and phenological changes on agricultural productivity in the black soil region of Northeast China under the background of climate change are not clear, the quantitative degree of future agricultural risk assessment is insufficient, and the risk level formulation lacks a basis. Therefore, based on remote sensing products, climate data and model simulations, this study integrated the logistic function fitting curvature derivation, multiple linear regression and scenario simulation to investigate the crop phenology dynamics and its climate response characteristics in this black soil region, and to identify the compound effects of climate and phenology changes on agricultural production and possible future risks. Results show that: (1) From 2000 to 2017, about 29.76% of the black soil region of Northeast China showed a significant delay in the onset of the growing season and 16.71% of the total area showed an advancing trend in the end of the growing season. The time lag effects of the onset of the growing season for crop response to climatic factors depended on site and climatic parameters, with the widespread influence of temperature and its lag time longer in general. (2) Both climatic and phenological changes have a significant effect on the interannual variability of crop production, and the explanatory capacity of both increased by 70.23% and the explanatory area expanded by 85.04% compared to that of climate change in the same period of the growing season. (3) Under RCP8.5 scenario, the future crop yield would show a decrease in the north and increase in the south, and when the global temperature rises by 2.0 ℃, the crop yield of southern Songnen black soil subregion would reduce by nearly 10%. Spatial and temporal variation of drought would adversely affect crop production. The study will help to understand the mechanisms underlying climate change, phenological response and productivity dynamics, and also help to strengthen the risk management of agro-meteorological disasters, which is important to ensure national food security and regional climate change response.

Long-term application of chemical fertilizers can lead to soil acidification, basic cation depletion, nutrient imbalance and heavy metal pollution of crops in farmland of Black Soil regions. Based on a 25-year National Black Soil Fertilizer Efficiency Monitoring Experiment in Gongzhuling, Jilin Province, the effects of 8 different fertilization treatments on soil acid neutralizing capacity (ANC) was examined, including no fertilization (Control or C), N, NP, NK, PK, NPK, combination of farmyard manure with chemical fertilizers (MNPK), and corn stalk return (SNPK). The application rates of N, P and K were 165, 36 and 68.5 kg hm^-2 a^-1, respectively, and N input was the same among NPK, MNPK and SNPK treatments. Results showed that chemical fertilizer application decreased topsoil pH by 0.37-1.39, while MNPK and SNPK treatments increased soil pH by 0.21 and 0.53, respectively. Acid neutralizing capacity as soil pH dropped to 5.0 (ANC_{pH 5.0}) of N, NP, NK, PK and NPK treatments was 42.85%, 61.79%, 54.05%, 82.26% and 63.68% of the Control, respectively, while the ANC_{pH 5.0} of MNPK treatment was 1.86 times of the Control. With 160 mmol kg^-1 H⁺ addition, the pH of SNPK-treated soil only decreased from 7.65 to 6.42, showing an extremely strong acid neutralizing capability. Soil exchangeable base cations were 1.37 and 1.14 times, while soil organic matters were 1.32 and 1.63 times, in SNPK and MNPK treatments as much as that in the Control, respectively, which are two main factors in improving soil ANC. In brief, the addition of organic materials significantly improved the anti-acidification properties and soil basic fertility level of the black soil. The results could provide theoretical basis and data support with long-term experiment evidence for the practices of conservation tillage with corn stalk return and chemical fertilizers partly substituted by farm-yard manure in black soil regions of Northeast China.