A comparison of different methods of decomposing maize straw in China

Abstract

It is important to understand the dynamics of crop residue decomposition in soils to predict the release of nutrients from remaining residues. The aim of this study is to investigate and monitor the nutrient release processes of crop residue decomposition in soils. For this, a nylon mesh bag method was used. Four maize straw treatments were investigated over a period of 150 days: (1) maize straw above ground placement (AG), (2) maize straw above ground with decomposer accelerator (AGDA), (3) below ground placement (BG), and (4) maize straw below ground/buried placement (BGDA). The decomposition of maize straw and nutrient release between the different treatments showed statistically significant differences. The effect of BG on maize straw decomposition was higher than AG due to better moisture, soil, and microbial contact conditions underground (incorporation) than above ground. However, the effect of the decomposer accelerator (DA) was not significantly different from the other treatments in this study. This may be due to DA being unsuitable for the local area and climate. The rate of maize straw mass decomposition in all four treatments varied from 38.9% (AGDA) to 66.3% (BG) in 150 days. Below ground placement was better for maize straw decomposition than above ground placement, hence it is advisable to incorporate the maize straw residues into the soil rather than leaving it on the soil surface. The organic C mineralization rate varied between 43.2% and 65.9%. The N release rates ranged between 51.1% and 67.7%, for P 76.0–89.8%, and for K release 76.9–91.7%. The release of potassium was higher than 80%, indicating the necessity of less potassium applied in fertilizer. To sum up, incorporating maize straw residues in the soil increases the C pool and nutrient release compared to surface placement.