Straw return impacts on crop yield and yield variability: A meta-analysis

Abstract

Crop yield variability is important for global food security. Numerous studies have shown that straw return can increase crop yields by improving soil properties and nutrient supply. However, past studies have not demonstrated whether and how straw return affects yield variability. A meta-analysis was conducted to investigate straw return effect on crop yields and yield variability as well as their driving factors associated with soil properties, management practices and climate conditions. The meta-analysis summarized the results from 44 experimental sites and illustrated that the effect of straw return on yield did not differ between short-term and longer-term experiments, but longer-term straw return reduced yield variability. Specifically, straw return treatment resulted in a 27 % increase in yield variability in the short-term studies, but only an 18 % increase in yield variability in the longer-term experiments. Soil properties and N, P or K input influenced the response of crop yields and yield variability to straw return practices. The effect of straw return on crop yields was more obvious in slightly alkaline soils with higher pH value (pH >7.3) and lower total nitrogen content (TN ≤1). Straw return with low N, P or K inputs not only increased crop yields but also reduced yield variability. Straw return treatment with low N and P input reduced yield variability by 19 % and 23 %. Mean annual precipitation was another driving factor affecting crop yield response to straw return. The effect of straw return on crop yields increased with the increase of mean annual precipitation from 500 mm to 1200 mm. In contrast, straw return treatments tended to reduce crop yields when mean annual precipitation was below 500 mm or above 1200 mm. Our study clearly showed that straw return practices with low N and P input can ensure long-term yield stability in areas with suitable rainfall (500–1200 mm) and slightly alkaline soil.