Water retention and warming effect of integrated rice management for the hilly areas of southwest China

Abstract

Seasonal drought and low temperatures strongly limit rice (Oryza sativa L.) grain yield in the hilly areas of Southwest China. An integrated rice management (IRM) system was developed, which integrates ridge cultivation with plastic mulching, furrow irrigation, and triangular transplanting. A field experiment was conducted from 2011 to 2015. The effects of IRM on grain yield, yield components, soil moisture content (θ), and soil temperature (Tsoil) were evaluated. Compared with traditional rice management (TRM), IRM significantly improved grain yield by 29.9%. Furthermore, the yield of IRM (8181−9267 kg ha−1, CV: 7.6%) remained relatively stable. The rice tiller of TRM was highly related to the accumulated rainfall during the rice tillering stage in drought years (2011 and 2014). The water retention capability of IRM decreased the influence of interannual rainfall on rice growth and grain yield. In 2015, the θ in the 0−20‐cm layer was higher than the threshold for rice root growth over the rice‐growing season. Compared with TRM, Tsoil of the 0−20‐cm layer in IRM was 4.7 °C higher during the early tillering stage. The >10 °C soil effective accumulated temperature in IRM was also higher, and the difference was highest at the maximum tillering stage. The warming effect of IRM, particularly during the tillering stage, stimulated early growth and stronger tillering. In summary, the water retention capacity and warming effect of IRM were key factors for the improvement of rice yield; most importantly, the yields were stabilized in both drought and rainy years.

Ground Cover Rice Production System Affects Soil Water, Nitrogen Dynamics and Crop Growth Differentially with or without Climate Stress

“…Since rice tillering was a major factor influencing PT, which directly determined crop yield [30], the correlation analysis between the tiller numbers and cumulative rainfall during the tillering period for different water management practices (Table 2) revealed that there was no significant correlation between rice tiller numbers and cumulative rainfall during the tillering period in 2021 and a significant correlation in 2022. This indicates that rice tillering in a dry year is directly affected by rainfall while tillering in a wet year is not affected by rainfall, which is consistent with the results of a previous study [34]. Meanwhile, the tiller numbers in 2022 were significantly higher in the GCRPS than in the Paddy (Figure 4), so it can be further speculated that GCRPS had a better effect in increasing the yield in the dry year.…”

“…Compared with the Paddy, Cheng et al [36] found that GCRPS reduced the soil water content in the hilly areas of Zhejiang Province, China. However, Dong et al [34] showed that the effect of GCRPS on the soil water content was not significant in our study region. Zhao et al [37] concluded that although GCRPS has less irrigation, evaporation through the soil's surface can condense into droplets and return the evaporated water to the soil when blocked by the film, resulting in only a little difference in the soil water content between GCRPS and Paddy.…”

“…In 2021, the rainfall in our study area was 1268 mm, which was higher than the multiyear average rainfall of 966 mm, and rainfall during the rice growth period reached 906 mm (Figure 9), which was higher than the average rainfall during the growth period of 715 mm over the past 15 years [34], so there was no seasonal drought in this year. The temperature in the early growth period was higher than 14 • C during this year (Figure 9), which was within the suitable temperature range for rice growth [32], and there was no early low-temperature stress.…”

“…Meanwhile, some studies also determined the drivers of crop yield under GCRPS via differences in the soil water and N content under different water management practices, and the results showed that the differences in soil water and N content were not significant [34,43]. Our results indicate that GCRPS did not significantly affect the SWS and SMN content, nor did it affect crop yield through indirect effects on both (Figure 8), suggesting that the soil water and N content were not drivers of crop yield under GCRPS, mainly because GCRPS increased soil mineral N mineralization, but crop N uptake also increased, resulting in the non-significant effect of GCRPS on soil N content.…”

“…Reports on the effect of GCRPS on soil water content do not have direct comparisons with the results of the traditional flooding paddy system, and the differences between them are not very clear. Prior studies have been conducted to determine the impact of GCRPS on crop growth; however, the conclusions are also mixed, with GCRPS either promoting or inhibiting crop growth and increasing or decreasing yields [18,[32][33][34]. Consequently, the effects of GCRPS on soil water, N content, and crop growth remain uncertain, and the indirect effect pathways of GCRPS on crop yield are not well defined.…”