Long-Term Green Manure Rotations Improve Soil Biochemical Properties, Yield Sustainability and Nutrient Balances in Acidic Paddy Soil under a Rice-Based Cropping System

Abstract

Cultivation of green manure (GM) crops in intensive cropping systems is important for enhancing crop productivity through soil quality improvement. We investigated yield sustainability, nutrient stocks, nutrient balances and enzyme activities affected by different long-term (1982–2016) green manure rotations in acidic paddy soil in a double-rice cropping system. We selected four treatments from a long-term experiment, including (1) rice-rice-winter fallow as a control treatment (R-R-F), (2) rice-rice-milkvetch (R-R-M), (3) rice-rice-rapeseed (R-R-R), and (4) rice-rice-ryegrass (R-R-G). The results showed that different GM rotations increased grain yield and the sustainable yield index compared with those of the R-R-F treatment. Compared with those of R-R-F, the average grain yield of early rice in R-R-M, R-R-R, and R-R-G increased by 45%, 29%, and 27%, respectively and that of late rice increased by 46%, 28%, and 26%, respectively. Over the years, grain yield increased in all treatments except R-R-F. Green manure also improved the soil chemical properties (SOM and total and available N and P), except soil pH, compared to those of the control treatment. During the 1983–1990 cultivation period, the soil pH of the R-R-M treatment was lower than that of the R-R-F treatment. The addition of green manure did not mitigate the soil acidification caused by the use of inorganic fertilizers. The soil organic matter (SOM), total nitrogen (TN) and total phosphorus (TP) contents and stocks of C, N and P increased over the years. Furthermore, GM significantly increased phosphatase and urease activities and decreased the apparent N and P balances compared with those in the winter fallow treatment. Variance partitioning analysis revealed that soil properties, cropping systems, and climatic factors significantly influenced annual grain yield. Aggregated boosted tree (ABT) analysis quantified the relative influences of the different soil properties on annual grain yield and showed that the relative influences of TN content, SOM, pH, and TP content on annual crop yield were 27.8%, 25.7%, 22.9%, and 20.7%, respectively. In conclusion, GM rotation is beneficial for sustaining high crop yields by improving soil biochemical properties and reducing N and P balances in acidic soil under double- rice cropping systems.

Impacts of long-term inorganic and organic fertilization on phosphorus adsorption and desorption characteristics in red paddies in southern China

“…These results could be due to the manure addition, which supplies enough nutrients to the soil, primarily by directly increasing carbon inputs into the soil, which assists in carbon sequestration. Similar results were reported in previous long-term studies [ 39 , 40 ]. Long-term NPK plus manure addition significantly increased the soil total P and available P concentrations in the soil at all three sites ( Table 3 ).…”

Sustainable Cropping Systems

“…The article by Qaswar et al [29] summarizes a long-term study on green manure rotations on an acidic paddy soil in a double rice (Oriza sativa L.) cropping system. Compared to a rice-rice-winter fallow cropping system, replacing winter fallow with a green manure crop improved grain yield and the sustainable yield index of early and late rice, soil organic matter, soil total and available N and phosphorus, and phosphatase and urease activities, and reduced the apparent N and phosphorus balances.…”

Reduced basal and increased topdressing fertilizer rate combined with straw incorporation improves rice yield stability and soil organic carbon sequestration in a rice–wheat system

“…Long-term experiments offer important advantages relative to short-term studies in providing valuable information on the effect of fertilization management on the sustainability of crop production (Manna et al, 2005;Qaswar et al, 2019;Han et al, 2020). Studies have reported that the sustainable yield index (SYI) of rice and wheat has a positive relationship with SOC content (Wanjari et al, 2004;Qaswar et al, 2019). These findings suggest that SOC plays an important role in improving crop yield stability under climate change (Manna et al, 2005;Han et al, 2020;Shi et al, 2022).…”