Integrated Soil-crop System Management Research Articles

Net global warming potential and greenhouse gas intensity of annual rice–wheat rotations with integrated soil–crop system management

The impact of management practices on the net global warming potential (GWP) and greenhouse gas intensity (GHGI) of rice cropping systems is not well documented. A field experiment was established in 2009 to gain insight into the net ecosystem carbon budget and the net GWP and GHGI on the crop seasonal scale over two cycles of rice–wheat rotations. With the local farmer's practices (FP) as the control, three integrated soil–crop system management (ISSM) practices at different nitrogen (N) application rates were established – ISSM-N1, ISSM-N2 and ISSM-N3 – for improvement of rice yield and agronomic nitrogen use efficiency (NUE). Compared with the FP, the rice yields significantly increased by 8.2%, 18% and 31%, while the agronomic NUE increased by 68%, 74% and 99% for ISSM-N1, ISSM-N2 and ISSM-N3, respectively. Within the three ISSM practices averaged over the two cycles, the soil organic carbon sequestration potentials, CH4 and N2O emissions were estimated to be 0.089–0.67tCha−1yr−1, 166–288kgCH4Cha−1yr−1 and 4.27–5.47kgN2ONha−1yr−1, respectively. Compared to the net GWPs (8.36tCO2eqha−1yr−1) and GHGI (0.58kgCO2eqkg−1 grain) from the FP, the ISSM-N1 and ISSM-N2 reduced both the net GWPs and GHGIs to some extent, indicating that GHG mitigation can be simultaneously achieved with improved food production and NUE. Although it produced similar GHGIs, the ISSM-N3 increased the net GWPs by 16% compared to the FP, indicating that more research is required on ISSMs for mitigating GHGs to further increase the grain yield and NUE in rice agriculture.

Understanding production potentials and yield gaps in intensive maize production in China

Understanding yield potentials and exploitable gaps in current intensive maize (Zea mays L.) production is essential in order to increase grain yields to meet future food requirements amid strong competition for limited resources. In this study, we used simulations with the Hybrid-Maize Model (http://www.hybridmaize.unl.edu/), highest recorded yields published in the literature, field experiments, and farm survey data to assess yield potentials and gaps in four maize agro-ecological regions of China. In 50 simulations of high-yield sites across China from 1990 to 2009, the yield potential averaged 16.5Mgha−1 for irrigated maize and 13.9Mgha−1 for rainfed maize, respectively. During the same period, the highest recorded yield was 15.4Mgha−1, or 93% of the yield potential of irrigated maize. In comparison, the average farmer's yield was 7.9Mgha−1 based on 5584 farms surveyed in 2007–2008. Consequently, the yield gap between the average farmer's yield and the modeled yield potential (YGM) was 8.6Mgha−1 for irrigated maize and 6.0Mgha−1 for rainfed maize and so farmers attained 48–56% of the yield potential. The yield gap between the average farmer's yield and highest recorded yield (YGR) was 7.6Mgha−1, so farmers attained 51% of the recorded yield. Because the sites used for simulated and recorded yields possessed the most favorable combinations of soil and crop management, closing the gaps in YGM and YGR in farmers’ fields within a short time frame could be very difficult. The attainable yield was collected from field experiments, which were conducted in farmers’ fields by farmers using recommended management practices by local agronomists. The data for attainable yield averaged 12.3Mgha−1 according 137 field experiments across China. The yield gap between the average farmer's yield and the experimental yield (YGE) was 4.5Mgha−1, with farmers attaining 64% of the experimental yield. The main factor explaining this gap was inefficient crop management practices, which constrained yield improvements in farmers’ fields. In order to narrow this gap, multidisciplinary understanding and cooperation among the disciplines of plant science, agronomy, soil science, agro-ecology and extension, resulting in integrated soil–crop system management, are essential.

Integrated Soil-Crop System Management: Reducing Environmental Risk while Increasing Crop Productivity and Improving Nutrient Use Efficiency in China

During the past 47 yr (1961-2007), Chinese cereal production has increased by 3.2-fold, successfully feeding 22% of the global human population with only 9% of the world's arable land, but at high environmental cost and resource consumption. Worse, crop production has been stagnant since 1996 while the population and demand for food continue to rise. New advances for sustainability of agriculture and ecosystem services will be needed during the coming 50 yr to reduce environmental risk while increasing crop productivity and improving nutrient use efficiency. Here, we advocate and develop integrated soil-crop system management (ISSM). In this approach, the key points are (i) to take all possible soil quality improvement measures into consideration, (ii) to integrate the utilization of various nutrient resources and match nutrient supply to crop requirements, and (iii) to integrate soil and nutrient management with high-yielding cultivation systems. Recent field experiments have shed light on how ISSM can lead to significant increases in crop yields while increasing nutrient use efficiency and reducing environmental risk.

Integrated soil–crop system management for food security

China and other rapidly developing economies face the dual challenge of substantially increasing yields of cereal grains while at the same time reducing the very substantial environmental impacts of intensive agriculture. We used a model-driven integrated soil-crop system management approach to develop a maize production system that achieved mean maize yields of 13.0 t ha(-1) on 66 on-farm experimental plots--nearly twice the yield of current farmers' practices--with no increase in N fertilizer use. Such integrated soil-crop system management systems represent a priority for agricultural research and implementation, especially in rapidly growing economies.