Decomposition characteristics of cotton stalks from fall to spring as affected by continuous cropping

Abstract

ABSTRACTKnowledge about cotton (Gossypium hirsutum L.) stalk degradation is important for understanding nutrient cycling in soil. The objective of this experiment was to study the effects of continuous cropping on cotton stalk decomposition and nutrient release patterns from fall to spring. Cotton stalks were placed inside nylon mesh bags on 5 October and then buried 15 cm deep in fields that had been continuously cropped to cotton for 1, 10, or 20 yrs. The results showed that the decomposition rates (i.e. mass loss) were significantly greater in the 10- and 20-yr soils than in the 1-yr soil during the first 16 d after burial. The decomposition rates were similar in all three soils between d 16 and 177. However, between d 177 and 193, the decomposition rates were the highest in the 1-yr soil. Overall, stalk mass declined by 35–40% during the 193 d experiment. The largest decreases in stalk mass were in the 1- and 10-yr soils. After 193 d, 95–97% of stalk K had been released compared with 29–34% of stalk P, and 41–48% of stalk N. The duration of continuous cropping had no significant effect on δ13C, N, and K release rates. The release rate of stalk P was the greatest in the 20-yr soil followed by the 1-year soil and then the 10-yr soil. In conclusion, the duration of continuous cotton cropping significantly affected the decomposition characteristics of cotton stalks. Additional studies will be done to learn more about how N application and irrigation can be managed in the fall so that (i) undecomposed residue does not interfere with spring sowing and (ii) the nutrients in the stalks are not lost after decomposition.