Soil organic carbon increment sources and crop yields under long‐term conservation tillage practices in wheat‐maize systems

Abstract

Long-term tillage and straw incorporation significantly affect soil organic carbon (SOC) sequestration and crop yield. However, the studies on the SOC sources under multicropping system are relatively few. The objective of this study was to evaluate the effects of conservation tillage on SOC and crop yields and distinguish the SOC sources from wheat (C3) and maize (C4). Therefore, the dynamics of SOC, SOC sequestration, and crop yield were evaluated during 15 years of conservation agriculture under conventional tillage (CT), subsoiling (ST), rotary tillage (RT), and zero tillage (ZT) without or with straw incorporation (CTS, STS, RTS, and ZTS, respectively). The results indicated that the highest mean SOC concentration in the 0-to 30-cm soil was found under STS (11.80 g kg −1 ), which increased by 2.29 g kg −1 than that under CT, whereas RT had the lowest mean SOC concentration (8.10 g kg −1 ). The increases in annual yield ranged from 0.58 (ZT) to 4.93 (ST) Mg ha −1 during 2005-2017. In comparison with the annual yield of CT, that of STS increased by 2 Mg ha −1 and was significantly higher than other treatments (p < .05) except ZTS and CTS. In comparison with CT, the SOC stock and carbon sequestration rate of STS were the highest and increased by 15.64 Mg ha −1 and 1.05 Mg ha −1 yr −1 , respectively, in the 0-to 30-cm soil. Moreover, the relative contribution of wheat residues to SOC was higher than maize residues under all treatments. Thus, subsoiling combined with C3 straw incorporation was more suitable for restoring degraded land and increasing yields. K E Y W O R D S 13 C, carbon sequestration, crop yield, soil carbon source, soil degradation

Increasing soil organic carbon sequestration and yield stability simultaneously through combined no-tillage and straw return in wheat-maize rotation

“…Results of the 8-yr study significantly enhanced SOC stocks under no-tillage with wheat straw stubbles 30-40 cm in height in the long term. This observation is consistent with the previous studies reporting that long-term no-tillage increases SOC stocks when crop residue retained in fields (Somasundaram et al, 2017;Gonçalves et al, 2019;Liu et al, 2020). In general, reduction of soil disturbance is one of main reason underlying the enhanced potential of SOC sequestration under adopting conservation agriculture (Kan et al, 2020;Sun et al, 2020).…”

“…However, increasing evidences from manipulative experiments (Zhao et al, 2019a;Li et al, 2019) and meta-analyses (Zhao et al, 2019b;Jat et al, 2020) have showed that adopting conservation agriculture (CA) could improve soil quality and agricultural sustainability. The CA mainly consists of various reduced and even no-tillage techniques with more than 30% of crop residue retained on soil surface, providing effective strategies for combating soil degradation (Liu et al, 2020). It has been reported that SOC contents of topsoil increased with years under CA for its superiority on the protection of soil structure and reduced rates of soil degradation (Somasundaram et al, 2017;Reeves et al, 2019).…”

A meta-analysis of the effects of crop residue return on crop yields and water use efficiency

“…The larger magnitude of increasing in crop yield was recorded for harrow plowing tillage, and chisel plow tillage in related to other tillage treatments. Similarly, Other studies showed that the main reasons proposed for the increased yield are that chisel plow tillage is conducive to the formation of a crop-favoring structure in the ploughed layer, promotes soil water infiltration, reduces soil bulk density, enhances rooting in the ploughing layer, enhances soil moisture movement, and promotes the absorption of nutrients and water by crop roots [47,48,49,50,51]. The results of Huang et al [52] and Xu et al [7] show that chisel plow tillage in conjunction with crop residue return can improve crop yields by promoting the accumulation and transfer of dry matter.…”

Management of Crop Residues for Improving Input Use Efficiency and Agricultural Sustainability

“…Crop residues offer multiple environmental services when retained in field conditions after harvest. A list of contributions has been recorded in different research articles; e.g., improving soil physical properties and contributing to soil organic carbon (SOC) formation [11][12][13]. Very often, crop residues are considered as waste materials, but they perform as a valuable resource when returned to the soil, and they deliver numerous ecosystem services to the environment [4].…”

“…Soil management with crop residues covers a wide range of aspects, like residue decomposition, soil erosion control, nutrient recycling and availability to plants, control of weed pests, and various conservation practices related to tillage for maximizing crop yields [10]. The annual cycling of plant nutrients is important in the plant-soil ecosystem in order to maintain a productive agricultural system and to facilitate better nutrient mobilization within the system [11]. It is reported that soil, air, and water, which have tremendous interaction with plants, release various essential inorganic nutrient elements for plant growth [7].…”