Restoring soil functionality and improving wheat yield through integrated farmyard manure, compost, crop residues and...

Wheat productivity is frequently constrained by the slow turnover of soil organic matter (OM), which limits nutrient mineralization and reduces their bioavailability to plants. In this context, the present study was conducted to assess the effects of different OM sources on wheat growth, phenological attributes, yield attributes, chlorophyll content and soil physicochemical properties, with a focus on improving sustainable nutrient management strategies for improving wheat productivity and soil health.

A field experiment was conducted over two consecutive winter seasons (2022-2023 and 2023-2024) at The University of Agriculture, Peshawar-Pakistan. The experimental design comprised two factors: (i) OM sources supplying 120 kg N/ha, including no residue (control), farmyard manure (FYM), compost, and wheat crop residues; and (ii) decomposition-enhancing materials (DM), namely control, Bio-organic phosphate (100 kg/ha), Bio-aab at the rate of 25 L ha^- 1 (microbial biofertilizer), and humic acid at the rate of 15 kg ha^- 1 was applied as leonardite-derived granular humic acid containing 70% humic substances. OM along with DM were incorporated into the soil 7 days before sowing under optimal field moisture conditions using a field cultivator. Wheat cultivar 'Pirsabak 2015' was sown at a seed rate of 120 kg/ha. Experiment was arranged in a RCB design with three replications. Individual plots measured 3 × 5 m and consisted of 10 rows with 30 cm inter-row spacing. The incorporation of OM delayed phenological development relative to the no-residue control. Among the tested treatments, FYM and compost consistently resulted in greater plant height (86.32 and 86.38 cm), spike density (236 and 239 m^- 2), grains number (45 and 45), grain weight (41.94 and 41.47 g), biological yield (10385 and 10385 kg ha^- 1), grain yield (2977 and 2998 kg ha^- 1), and chlorophyll content (chlorophyll a: 23.37 and 23.07; chlorophyll b 44.74 and 45.59; and total chlorophyll: 68.66 and 68.88). Among DM, humic acid improved wheat growth traits, including plant height (87 cm), spikes m^- 2 (245), grains spike^- 1 (46), grain weight (43 g), biological yield (10452 kg ha^- 1), grain yield (3013 kg ha^- 1) and chlorophyll content, compared with other treatments, resulting in better biomass accumulation. Regarding soil fertility, Bio-aab or Bio-organic phosphate combined with FYM or compost increased soil mineral nitrogen, organic matter, total nitrogen and organic carbon. The highest net income in economic analysis (279415 ha^- 1) was recorded in FYM + humic acid treatment. The highest value cost ratio (VCR) was observed in no residue + humic acid, followed by FYM + Bio-aab and FYM + humic acid.

Across both seasons, the combination of FYM and compost with humic acid improved crop growth and yield, while untreated plots recorded the lowest values. Integrated application of FYM or compost with humic acid, Bio-aab or Bio-organic phosphate is recommended to enhance wheat productivity and improve soil fertility under semi-arid conditions.