Effects of pelletized straw on soil nutrient properties in relation to crop yield

Poor soil-residue contact from field-chopped straw (CS) application restricts the efficient incorporation and rapid decomposition of crop residues in intensive cropping systems. Pelletized straw (PS), which has a high bulk density and relatively small size, can improve this contact, but its effect on soil fertility after incorporation is not well known. Therefore, a field experiment was conducted over four cropping seasons in Shandong Province, China, to evaluate the effects of corn CS and PS incorporation (6 t/ha) on soil organic carbon (SOC), available nitrogen (N), available phosphorus (P), available potassium (K), crop yields and economic benefits. Compared with the SOC and available N, P and K concentrations from 0 to 60 cm under the no straw incorporation (CK) treatment, the concentrations under the CS and PS treatments were higher but decreased gradually after treatment application. In the topsoil (0-20 cm) under the CS and PS treatments, these concentrations increased by 1.6% and 10.0%, by 18.5% and 25.8%, by 21.7% and 29.3%, and by 9.2% and 13.0%, respectively. Compared with the soil fertility in the CS plots, soil fertility in the PS plots improved, but significant differences were recorded only in the first season. The highest crop yield each season was obtained from the PS plots: wheat yields were 8.8% and 10.3% higher in the PS plots than those in the CS and CK plots, respectively, and corn yields were 2.8% and 16.9% higher, respectively. Furthermore, the net economic return averaged across 2 yr was 7.8% and 23.9% greater with the PS treatment than that with the CS and CK treatments, respectively. Thus, PS may constitute an efficient and economical approach for improving soil fertility and increasing crop yields in intensive cropping systems.