Long term manure driven nutrient cycling enhances productivity resilience and food security in semiarid agroecosystems

Abstract

Understanding the long-term effects of sustained organic inputs is essential for building resilient and sustainable agricultural systems in semiarid regions where soil fertility and productivity are declining. Yet, the multi-decadal impacts of manure additions, especially when combined with nitrogen (N) fertilization, on soil nutrient dynamics and crop productivity remain poorly quantified under uniform, long-term management. This study assessed the 56-year impact of farmyard manure (FYM) (0, 10, 20, 30 Mg ha⁻¹; F0, F10, F20, and F30, split equally between rabi and kharif seasons) combined with N fertilization (0, 60, 120 kg ha⁻¹) in an irrigated pearl millet-wheat system. Results revealed that, the average yield (2000–2023) of pearl millet (2.45 Mg ha − ¹) and wheat (4.77 Mg ha − ¹) in the F20 plots was statistically ( p < 0.05) comparable to F30 plots, and was 25% and 43% higher than control plots, respectively. The omission of N fertilization significantly diminished the yield potential, emphasizing its crucial importance in crop production. The soil organic carbon, nutrients supplying capacity, microbial functions and enzymes activity in soil were significantly higher in F30 plots. Continuous heavy dose of FYM (F30) application enhanced soil organic carbon 143% (surface) and 183% (subsurface) compared to control plots. Available phosphorus and potassium exhibited substantial increases, with surface soils showed 4.1 and 1.7-fold, and subsurface soils 6.2 and 2.7-fold increments, respectively over without FYM fertilized plots. Partial least squares path modeling (PLS-PM) revealed that macronutrients were the principal drivers of crop yield (path coefficient = 1.18, p < 0.001), accounting for 72% of yield variability and emphasizing the critical interplay of biotic and abiotic factors. Integration of 20 Mg ha⁻¹ FYM with optimum nitrogen fertilization may provide a scalable, climate-resilient solution to sustain yields, restore degraded soils, and can substantially strengthen food security in semiarid regions and comparable soil types, particularly under similar agroecological conditions.