Tillage, Residues Management, and Nitrogen Fertilization Effects on Soil Organic Status, Soil Quality, and Soft Wheat in the Moroccan Semi-Arid

Sustainable management of agricultural practices can improve soil organic status, soil quality (SQ), and yields. The study was conducted to test the impact of tillage (conventional (CT) and no-till (NT)), residues (vetch (C1) and uncover soil (C0)), and three nitrogen (N) fertilization rates (30, 60, and 90 N kg ha-1) on soil organic carbon (SOC), total nitrogen (N), C/N ratio, soft wheat yields and SQ. The experiment was established in 2010 in the Moroccan semi-arid. After ten years, the SOC concentration was greater under NT (9.4 g/kg) compared to CT (8.4 g/kg). Crop residues also enhanced SOC (10 g/kg) contrary to C0 (8.1 g/kg). Application of N fertilization showed profound effects on total N, increasing levels of N fertilization led to higher total N irrespective of tillage. Crop residues increased total N (0.6 g/kg) better than C0 plots at the horizon 20–40 cm. Soft wheat revealed an improvement under NT (4213.8 kg ha-1) versus CT (3785.6 kg ha-1) and it responded positively to the N application. For SQ evaluation through the indexing methods (SQI), principal component analysis was done for eight soil indicators to select the minimum data set (MDS), which were subsequently normalized and integrated into the SQI, additive (SQIANL), and weighted (SQIWNLM). NT revealed higher scores (0.52; 0.6) than the CT (0.46; 0.53) for SQIANL and SQIWNL, respectively, at the horizon 0–20 cm. the residues layer on the soil surface improved SQIWNL score (0.59) compared to C0 (0.55). Moreover, the correlation (r) with yield and the sensitivity (S), allowed us to choose SQIWNL, as the best index (highest r and S) to evaluate SQ under different practices studied. Indeed, SQIWNL revealed an intermediate SQ under NT and at C1 treatments, compared to CT and C0 (low SQ).