Benefits and limitations of straw mulching and incorporation on maize yield, water use efficiency, and nitrogen use efficiency

Straw mulching and straw incorporation are widely used for conservation tillage as the primary methods of returning straw to the field. However, few studies have investigated the effects of straw mulching and straw incorporation under various agronomic management and environmental and edaphic factors. Here, we conducted a meta-analysis incorporating 112 publications to determine whether straw incorporation and straw mulching had different effects on maize yield, water use efficiency (WUE), and nitrogen use efficiency (NUE) under contrasting soil textures, N application rates, straw returning amounts, and annual average precipitation, temperature, and evaporation. The results showed that straw mulching and straw incorporation significantly increase maize yields, WUE, and NUE. Straw mulching yield had a significant positive correlation with WUE, while straw incorporation yield had significant positive correlations with WUE and NUE. Maize yield and WUE increased and NUE decreased with increasing nitrogen application rate. Straw incorporation increased maize yield and NUE more than straw mulching at low straw returning amounts (< 6000 kg ha-1). In arid and semi-arid areas with 400 mm average annual precipitation and 7 <degrees>C, while straw incorporation is more conducive to increasing maize yield, WUE, and NUE with average annual temperatures 13 degrees C. Of the three soil textures, the largest weighted response ratio of straw returning on yield and NUE occurred in loam soil with straw incorporation. This study identified the benefits and limitations of straw incorporation and straw mulching on maize yield, NUE, and WUE.