Compost from Date Palm Residues Increases Soil Nutrient Availability and Growth of Silage Corn (Zea mays L.) in an Arid Agroecosystem

Improving soil fertility using crop residues is essential for circular agriculture in arid agroecosystems such as oases. This study aimed to evaluate effects of composts based on palm leaves on nitrogen (N) mineralization, soil properties, silage corn yield, and nutrient uptake in oasis agroecosystems. A 2-year field study was performed to compare impacts of two composts, one based on dry palms and rock phosphate (C1, C:N > 30) applied at 25 t ha(-1), and the other based on dry palms, rock phosphate, and sheep manure (C2, C:N = 17) applied at three rates (10, 25, and 40 t ha(-1)). The fifth treatment included application of only mineral N fertilizer (MNF). The sixth treatment received no fertilizer (control). The compost-amended plots had significantly higher organic matter, total N, and available phosphorus (P) and potassium contents in the soil after silage corn harvest in both seasons than MNF and control plots did. Applying compost C2 resulted in net N mineralization in both seasons, while applying compost C1 resulted in N immobilization in the second season. Mean dry biomass yield was 21.6 and 21.0 t ha(-1) with MNF and 40 t ha(-1) of C2 in the first year, respectively, and 21.3 and 19.1 t ha(-1) in the second season, respectively. Increasing the compost application rate significantly increased yields in both seasons. Applying either compost resulted in higher P uptake at silage corn harvest than applying MNF. Recycling date palm residues as compost improves soil fertility and forage production, which promotes sustainable farming systems in arid regions.