Frequent Irrigation Under Increasing Doses of Stabilized Sewage Sludge in The Soil Increases the Yield and Quality of Silage Maize

Abstract

Achieving higher efficiency and better quality production with appropriate irrigation regimes in silage maize cultivation in soils mixed with urban sludge is a requirement of sustainable agriculture. Therefore, a two-year field study was carried out with three replicates with four different sewage sludge doses (D0: 0 t/ha, D1: 30 t/ha, D2: 60 t/ha, and D3: 90 t/ha), and three different irrigation regimes (S1, S2, and S3). In the S1, S2 and S3 regimes, when the sum of (Reference evapotranspiration - Effective rainfall) was 25 mm, 50 mm and 75 mm, respectively, irrigation was carried out and the soil moisture deficit was completed to the field capacity. Considering the two-year average, increasing sewage sludge dose and frequent irrigation significantly increased fresh and dry biomass yields and crude protein, while decreasing acid detergent fiber (ADF) and neutral detergent fiber (NDF). The fresh biomass yield in D3 treatment was 12.4%, 20.6%, and 42.1% higher than D2, D1, and D0, respectively. ADF in D3 was 5.6%, 2.1% and 1.7% lower than D0, D1 and D2, respectively, while NDF was 4.4%, 3.7% and 2.1% lower. D3 treatment increased the crude protein value by 27.3%, 15.5% and 7.7% compared to D0, D1 and D2 treatments, respectively. S1 provided 12.9% and 28.3% higher fresh biomass yield compared to S2 and S3. ADF value in S1 was 0.69% and 2.4% lower than S2 and S3, respectively, and NDF value was 0.86% lower compared to S3. There was a positive linear relationship with a high correlation between fresh and dry biomass yields. It could be concluded that D3-S1 treatment is the most effective practice for higher and quality yields, and followed by D3-S2 treatment.

Keywords

• adf
• ndf
• crude protein
• dry and fresh biomass
• irrigation regime
• sewage sludge