Significance The world has been struggling to find sustainable ways to increase crop production to satisfy the needs for food, feed, fiber, and industrial uses while reducing negative environmental impacts. This challenge is magnified in countries/regions where the availability of farmable land for agriculture is limited. We developed an integrated cropping system that incorporates key farming tactics. Tested in 16 field experiments over 12 consecutive years (2006 to 2017), the integrated system increased crop yields while decreasing the environmental footprint. The integration enables significant synergies in biophysical processes to occur under a wide range of crop inputs, suggesting that system integration can be adopted globally for a range of smallholder farming.
Abstract Intercropping increases the grain yield to feed the ever-growing population in the world by cultivating two crop species on the same area of land. It has been proven that N-fertilizer postponed topdressing can boost the productivity of cereal/legume intercropping. However, whether the application of this technology to cereal/cereal intercropping can still increase grain yield is unclear. A field experiment was conducted from 2018 to 2020 in the arid region of northwestern China to investigate the accumulation and distribution of dry matter and yield performance of wheat/maize intercropping in response to N-fertilizer postponed topdressing application. There were three N application treatments (referred as N 1 , N 2 , N 3 ) for maize and the total amount were all 360 kg N ha −1 . N fertilizer were applied at four time, i.e. prior to sowing, at jointing stage, at pre-tasseling stage, and at 15 days post-silking stage, respectively. The N 3 treatment was traditionally used for maize production and allocations subjected to these four stages were 2:3:4:1. The N 1 and N 2 were postponed topdressing treatments which allocations were 2:1:4:3 and 2:2:4:2, respectively. The results showed that the postponed topdressing N fertilizer treatments boosted the maximum average crop growth rate (CGR) of wheat/maize intercropping. The N 1 and N 2 treatments increased the average maximum CGR by 32.9% and 16.4% during the co-growth period, respectively, and the second average maximum CGR was increased by 29.8% and 12.6% during the maize recovery growth stage, respectively, compared with the N 3 treatment. The N 1 treatment was superior to other treatments, since it increased the CGR of intercropped wheat by 44.7% during the co-growth period and accelerated the CGR of intercropped maize by 29.8% after the wheat had been harvested. This treatment also increased the biomass and grain yield of intercropping by 8.6% and 33.7%, respectively, compared with the current N management practice. This yield gain was primarily attributable to the higher total translocation of dry matter. The N 1 treatment increased the transfer amount of intercropped wheat by 28.4% from leaf and by 51.6% from stem, as well as increased the intercropped maize by 49.0% of leaf, 36.6% of stem, and 103.6% of husk, compared to N 3 treatment, respectively. Integrated the N fertilizer postponed topdressing to the wheat/maize intercropping system have a promotion effect on increasing the translocation of dry matter to grain in vegetative organs. Therefore, the harvest index of intercropped wheat and maize with N 1 was 5.9% and 5.3% greater than that of N 3 , respectively. This demonstrated that optimizing the management of N fertilizer can increase the grain yield from wheat/maize intercropping via the promotion of accumulation and translocation of dry matter.
Reducing carbon emissions from agricultural soils contributes to global greenhouse mitigation. Although the integration of no-tillage practices into maize/pea intercropping systems can achieve this reduction, the specific microbial mechanisms involved remain unclear. This study aimed to explore the effects of integrating maize/pea intercropping and no-tillage technologies on soil carbon emissions and microbial communities. The results indicated that intercropping no-till maize with peas reduced the average soil respiration rates by 19%. In 2021 and 2022, intercropping no-till maize with peas decreased soil carbon emissions by 25.1 and 30.4%, respectively. This practice resulted in a reduction of soil microbiota carbon and nitrogen by 26.9 and 19.7%, respectively, while simultaneously increasing the soil microbial gene beta diversity. Proteobacteria, Actinobacteria, Planctomycetes, Firmicutes, Bacteroidetes, and Acidobacteria collectively represented over 95% of the population and were predominant across all treatments. Intercropping no-till maize with peas decreased the abundance of carbohydrate-active enzymes in the soil. The structural equation modeling indicated that combined no-tillage and intercropping practices effectively decreased soil carbon emissions by modulating the community structure of soil microorganisms. This affected the abundance of carbohydrate-active enzymes and carbon-metabolizing genes in the soil. This study indicated that no-tillage and intercropping methods contributed to carbon reduction by influencing soil microbes. This study can provide microbial-level insights for refining agronomic practices to mitigate soil carbon emissions.
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