Effects of subsoiling rotational patterns with residue return systems on soil properties, water use and maize yield on the semiarid Loess Plateau

Highlights

• NCS can effectively improve soil physical property and yield.

• Long-term maize cultivation decreased deep soil water, especially in subsoiling.

• The effect of soil water on yield is great than soil physiochemical properties.

Abstract

In recent years, conservation rotational tillage has been proposed to regulate soil physicochemical properties and improve soil productivity. However, the response of soil productivity to different rotational tillage with residue return systems remains unclear. Based on this concept, a long-term experiment (2007–2019) concerning conservation rotational tillage with residue-returned was established with four tillage treatments: (1) no-tillage was set at the first year, conventional tillage was set at the second year, and the third year was set with subsoiling (NCS); (2) the first year was set with no-tillage then rotated with subsoiling in the second year (NS); (3) the first year was set with subsoiling then rotated with conventional tillage in the second year (SC); (4) subsoiling (S) was set each year as the control, and all tillage took place after the residue return. After a 12-year in situ tillage experiment, NCS and SC significantly reduced soil bulk density (BD) by 7.4 % and 13.2 %, respectively, and increased soil porosity by 8.8 % and 14.6 %, respectively, in the 0−20 cm soil depth. Meanwhile, NCS, NS and SC increased the macroaggregates by 27.4 %, 22.4 % and 30.0 %, respectively, at the 0−40 cm soil depth, and NCS significantly increased aggregate stability compared with S. For the effect of different tillage practices on soil nutrients, SC slight increased annual average soil organic (SOC) and total nitrogen (TN) by 4.5 % and 7.2 % compared with S. In addition, the soil water balance showed a negative trend of consumption, but NCS, NS and SC mitigated water consumption at the 0−200 cm soil depth, especially in dry years. The 12-year spring maize cultivation consumed soil water storage at a 120−420 cm soil depth, especially in ST, which increased this factor by 28.7 %–34.1 % when compared with others. In normal year, NCS significantly increased yield by 3.7 %–10.4 % compared with others. Considering the effect of the long-term experiment, NCS increased the annual average yield, WUE and PUE by 5.2 %, 4.7 % and 5.6 % compared with S, respectively. Based on the comprehensive Z-index score, the NCS with residue return was selected as the recommended agricultural management measure suitable for the climate-similar region of the Loess Plateau.

Introduction

As a primary rainfed production area, the degradation of soil and a shortage of water resources are the main factors that limit agricultural development in the Loess Plateau, China (Aziz et al., 2013; Wang et al., 2018). And these stress effects are reinforced by unsuitable soil management practices, which involve plowing with straw removal and intensive soil disturbance. Intense and frequent soil disturbance has been proven to accelerate soil erosion, degradation and environmental pollution and will lead to lower soil productivity (Garcia-Marco et al., 2016). Therefore, formulating rational agricultural management systems to restoring degraded soil and water storage are the keys to improving soil productivity, which is conducive to ensuring food security and agricultural development.

Due to limited rainfall or geographical conditions, there is a long fallow period of approximately 180 days every year in maize production on the Loess Plateau, and the major challenge in this region and other similar areas is to store water and enhance soil nutrients in this time quantum (Tuure et al., 2021; Zhang et al., 2019b). Conservation tillage with less soil disturbance can preserve the natural soil state as much as possible and is considered to be an effective water conservation management measure (Sithole et al., 2016). In recent years, subsoiling has been widely promoted as an important part of conservation tillage by eliminating soil compaction, improving soil structure and increasing the infiltration of rainfall water (He et al., 2007; Soane et al., 2012). Previous research has shown that subsoiling improves grain yield and WUE by 14.4 % and 9.2 %, respectively, compared with conventional tillage (Sun et al., 2018). However, it has been reported that after three planting seasons with continued subsoiling, this tillage practice has almost no effect on plant growth, and long-term subsoiling will increase soil nutrient enrichment in surface soil (Ma et al., 2015). Therefore, for the purpose of overcoming the shortage of subsoiling, conservation rotational tillage has been proposed as the main agricultural management measure to achieve long-term soil structure, water conditions and yield improvement. Studies on combined tillage systems with subsoiling and no-tillage have shown that this system could improve soil properties and significantly increase wheat yields and WUE by 10.15 % and 7.5 %, respectively, over conventional tillage (Hou et al., 2012; Tian et al., 2016). Meanwhile, this tillage system has also been shown to be good for soil nutrient status, which improves the soil organic carbon stock compared with conventional tillage and is a major strategy for improving soil productivity (Valboa et al., 2015). Therefore, subsoiling and no-tillage measures are the preferred choice for rotational tillage systems. However, the advantages of conventional tillage have been ignored in scientific research. For example, conventional tillage can effectively reduce weeds by more than 50 % compared to no-till or reduced tillage, and the burial of residue is conducive to increasing soil nutrition for deep soil (Peigné et al., 2018). Therefore, the effect of optimizing a subsoiling tillage system that incorporates no-tillage and conventional tillage in improving soil productivity is necessary to explore.

Residues rich in nutrients and the return of residue will improve soil properties, while the residue under different tillage practices changes its influence on soil properties (Sharma et al., 2021). Residue direct mulching on the surface is beneficial to reducing soil water evaporation and increasing topsoil nutrients (Lenka and Lal, 2013). Burying residue at approximately 20 cm with a plow increases soil organic matter in the 20−40 cm soil depth by 45.9 % and decreases soil bulk density by 2.4 % after long-term residue return (Zhang et al., 2018). Although previous experiments have extensively explored no-tillage, subsoiling, conservation tillage and residue use strategies, their combined effects on yield increase remain unknown.

We hypothesize that the change of tillage system will benefit to physicochemical properties, soil water condition and yield. Therefore, our aim is to incorporate no-tillage, subsoiling, conventional tillage and residue return and form a comprehensive agricultural management system based on subsoiling to sustainably improve soil productivity. And the understanding about this paper is conducive to how to use subsoiling practices in agricultural production to enhance soil productivity.