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Inappropriate spatial distribution of canopy and roots limits further improvements to the grain yield of maize with increased planting density. We explored an integrated management practice called strip deep rotary with staggered planting (SRS) which includes comprehensive technology for both canopy layers and topsoil. Here, field experiments were conducted under two maize cropping systems (spring maize and summer maize) to evaluate the effect of SRS on the spatial distribution of the canopy and roots for maize under high planting density (90,000 plants ha−1) and to determine the physiological factors involved in yield formation. Compared with conventional management practices (no-tillage with single planting, NTS), SRS decreased the LAI of the middle to top layers while improving the light distribution of the middle and lower layers by 72.99% and 84.78%, respectively. Meanwhile, SRS increased the root dry weight density and root sap bleeding by 51.26% and 21.77%, respectively, due to the reduction in soil bulk density by an average of 5.08% in the 0–40 cm soil layer. SRS improved the SPAD in the ear and lower leaves and maximized the LAD, which was conducive to dry matter accumulation (DMA), increasing it by 14.02–24.16% compared to that of NTS. As a result, SRS increased maize grain yield by 6.71–25.44%. These results suggest that strip deep rotary combined with staggered planting noticeably optimized the distribution of light in the canopy and reduced the soil bulk density to promote root vitality and growth, to maintain canopy longevity, and to promote the accumulation of dry matter, which eventually increased the grain yield of the maize under high planting density conditions. Therefore, SRS can be considered a better choice for the sustainable high yield of maize under high-density planting conditions in the NCP and similar areas throughout the world. [ABSTRACT FROM AUTHOR]

Huang-Huai-Hai Plain is the most important region for grain production in China. In this area, long-term rotary tillage in winter wheat and no tillage in summer maize have significantly increased soil bulk density, which impede maize root growth and reduce the grain yield. Subsoiling tillage is an effective practice to improve soil properties and crop growth. The objective of this study was to investigate the integrated effects of subsoiling tillage in both winter wheat and summer maize seasons on soil bulk density, maize root growth and spatial distribution. A two-year field experiment was conducted in winter wheat–summer maize rotation system. Tillage treatments included rotary tillage (RT) and subsoiling tillage (ST) in wheat season, and no tillage (NT), inter–row subsoiling tillage (STIR), and on–row subsoiling tillage (STOR) in maize season. It was found that in the second year, i.e., in 2018, ST decreased soil bulk density by 3.87% and increased porosity by 5.86% at 30–40 cm soil depth at maize maturity. Meanwhile, maize root length density at 40–50 cm depth increased by 30.00% and grain yield increased by 4.70% under ST. In maize season tillage treatments, STOR decreased soil bulk density by 4.52% and increased soil porosity by 6.96% at 20–30 cm soil depth. Compared with NT, the STOR significantly increased maize root length density at 20–30 cm soil depth by 78.45%, and increased root length density in a horizontal area 0–10 cm for both years, with a significant increase of 58.89% in 2018. Therefore, this study demonstrated that in the Huang-Huai-Hai Plain, which has a tidal soil type, subsoiling tillage in winter wheat season and on–row subsoiling tillage in maize season can loosen the soil and improve vertical extension of maize root system in the soil. [ABSTRACT FROM AUTHOR]

Wheat/soybean rotation is an important double-cropping system in the Huang-Huai-Hai plain of China. Continuous soybean cropping could cause soil quality deterioration and plant growth inhibition. However, the effects of continuous wheat/soybean cropping on soybean rhizosphere microbes remain largely unknown. In this study, we compared the soybean yield and rhizosphere soil microbial community between continuous winter wheat/summer soybean (W/S) with two harvests in one year and winter wheat/summer soybean-winter wheat/summer maize (W/S-W/M) with four harvests in two years. The results showed that the soybean yield in the W/S group significantly (p < 0.05) declined within the first two years. The W/S-W/M showed higher soybean yield and soil fertility index than the W/S group. The sequencing results revealed that cropping rotation had a higher impact on the fungal community than the bacterial community. The W/S group showed 22.08–23.01% higher alpha diversity of the fungal community, but the alpha diversity of the bacterial group did not vary significantly in this group. The fungal community composition in the W/S and W/S-W/M groups differed significantly. In the W/S-W/M group, a higher relative abundance of plant growth-promoting fungi (e.g., Mortierella), nematophagous fungi (e.g., Plectosphaerella), and biological control fungi (e.g., Coniothyrium) was observed. In the W/S group, a higher relative abundance of lignocellulose-degrading fungi (e.g., Trechispora, Myceliophthora, Botryotrichum, and Coniochaeta) and pathogenic fungi (e.g., Pyrenochaetopsis and Cyphellophora) was observed. LEfSe analysis demonstrated that Mortierella, Myceliophthora, and Trechispora could serve as crucial biomarkers. Mortierella was positively associated with available P levels and negatively associated with NO3−-N levels and pH while Trechispora showed the opposite trend. The findings of this study could enhance the current understanding of the mechanisms associated with the continuous wheat/soybean cropping obstacles and ensure the sustainability of agricultural production. [ABSTRACT FROM AUTHOR]