Incorporation of Crop Residues into Soil: A Practice to Improve Soil Chemical Properties

Abstract

Crop residues have the potential to enhance soil fertility, but this is dependent on their biochemical properties. This study aimed to evaluate the chemical composition, and nutrients release patterns of selected crop residues (corn stalk, rice straw, millet straw and sorghum stalk). Thus, 20 g of each crop residue were put in litter bags and placed in a plastic pot containing 10 kg of soil with a moisture content of 40% - 60%. Five replications were considered per type of residue and some samples were taken every 4 weeks. Results showed that crop residues got a pH varying between 5.09 and 6.5. The lowest C content (33.11%) and nitrogen (0.27%) were measured in sorghum stalk when the highest C content (47.6%) and nitrogen content (0.55%) were registered in corn stalk. The highest phosphorus content (0.58%) was got in corn stalk. Potassium content was higher in millet straw than in others. The highest calcium content (0.37%) and magnesium (0.29%) were found in rice straw. There was an increase of soil chemical composition after crop residues burial. Significant increase in carbon, nitrogen, and phosphorus content was noted in soil at week 4 with the highest at week 16. At the end of the experiment, the highest C content (53.1%) and the highest nitrogen content (0.88%) in the soil were observed after burial of rice straw. The highest phosphorus content (0.82%) registered in the soil was got with millet straw. Nutrient release efficiency of crop residues occurred in the following order: rice straw > millet straw > sorghum stalk > corn stalk. This study has demonstrated that rice straw and millet straw released nutrients faster and this is beneficial for early planted crops, while sorghum stalk and corn stalk released nutrients slowly which is appropriate for long-term availability of plant nutrients.