Decomposition and Nutrient Release of Selected Cereal and Legume Crop Residues

Abstract

Crop residues have the potential to enhance soil fertility, but this is dependent on their biochemical quality. A study was conducted at the National Semi-Arid Resources Research Institute-Serere, Uganda to determine the chemical composition, nutrient release patterns and rates of selected crop residues. The design used was randomized complete block design with four replications. The treatments comprised of 20g of finger millet, sorghum, cowpea and groundnut crop residues. Finger millet had the highest initial C (36.28%) and N (3.46%), cowpea had the highest initial P (0.60%) and Ca (0.30%) and groundnut shells had significantly the highest initial K (1.01%). Finger millet husks with the lowest carbon/nitrogen ratio, had significantly the highest rate of dry matter disappearance and nutrient release, while groundnut shells with the highest carbon/nitrogen and carbon/phosphorus ratios had significantly the lowest nutrient release and dry matter disappearance rates. At the end of incubation, finger millet husks had significantly the lowest N (0.29%) and C (10.22%), while cowpea husks had the lowest P (0.27%), K (0.18%) and Ca (0.27%). Nutrient release and dry matter disappearance rates of crop residues occurred in the order of N > K > P > Ca and finger millet husks > cowpea husks > sorghum husks > groundnut shells, respectively. This study has demonstrated that finger millet husks released nutrients faster and this is beneficial for early planted crops, while groundnut shells released nutrients slowly which is appropriate for long term availability of plant nutrients.

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

“…In fact, crop residues are important natural resources, and their effective recycling improves the soil physical, chemical and biological properties. Similar results were obtained by Anguria et al [21] in northeastern Uganda. Indeed, these authors observed high levels of nitrogen, phosphorus, and potassium in millet, sorghum, cowpea and peanut residues.…”

Assessing the Response of Sesame to Inorganic and Organic Nutrient Sources

“…This was attributed to optimum supply of N, P and K which promoted development of sesame reproductive structures. Significantly higher sesame seed yields observed in plots treated with 3 t/ha of finger millet husks plus lower fertilizer rate compared to other treatments, could be attributable to addition of sufficient quantities of organic C, N, P, K and Ca and enhanced soil moisture retention by finger millet husks (Anguria et al, 2017). In addition, lower fertilizer rate might have also added into soil optimum quantities of N, P and K nutrients.…”

“…Significantly higher sesame seed crude protein produced in plots treated with 6 t/ha of finger millet, higher fertilizer rate and a mixture of 6 t/ha of finger millet husks plus lower fertilizer rate is attributable to high N added into the soil (Anguria et al, 2017). High N supply could have enhanced its uptake that most likely promoted protein synthesis in sesame seeds.…”

Outputs: Potassium Losses from Agricultural Systems

“…The K concentration in the residue of agricultural crops varies widely, as does the rate of subsequent K release from the residue (e.g., Anguria et al 2017). Estimating both the quantity of crop residue and its K concentration are necessary steps for measuring the K in residues and the potential for K loss or recycling from residues remaining in the field.…”