Significant advances in plant-available and replenishable macro- and micronutrients with soil health-oriented conservation farming: Novel insights from a multi-site on-farm evaluation

Abstract

While conservation farming practices are known to increase soil health and ecosystem functioning, little is known about their effect on nutrient availability. In this study, we conducted an on-farm evaluation of conservation farming advances in plant-available and replenishable macro- and micronutrients.

Therefore, three different management systems (conventional farming, conservation farming, and an adjacent field margin as reference system) at 21 sites were sampled at three soil depths (0–5, 5–20 and 20–35 cm), and plant-available and replenishable nutrients were extracted by electro-ultrafiltration and subsequently measured by absorption and emission spectrophotometry.

Conservation farming systems significantly increased both plant-available and replenishable nutrient fractions as compared to conventional farming systems. In particular, both fractions of N_org, P, S and K were strongly elevated through conservation farming; plant-available S contents in the conservation farming system were even higher than in adjacent field margins. Using multiple linear regression analyses, we could further show that microbial necromass is significantly positively linked to both plant-available and replenishable N, N_org, P and S contents, suggesting that this agriculturally manageable microbial fraction is highly important for nutrient availability and replenishment. Moreover, soil pH, cation exchange capacity and soil organic carbon contents strongly influence plant-available and replenishable cations such as N, P, Ca, Mg or B.

Through a more targeted fertilization management (as in the case of S and B) and significant soil health advances (i.e., higher soil organic matter contents, better soil structure), conservation farming systems provide a solid foundation to ensure long-term, sustainable crop production.