Soil chemical properties under no‐tillage as affected by agricultural trophic complexity

Abstract

Abstract Soil fertility under no‐tillage farming may be affected by agricultural complexity. By transforming most of the ingested pasture into urine and faeces, ruminants catalyse nutrient cycling by breaking down complex plant molecules, which can help to maintain or even improve soil fertility. We evaluated how integrating annual crops and the ruminant grazing of cover crops in the same land area and at overlapping times affect soil fertility in no‐tillage systems. Soil chemical properties were evaluated at 0–5‐cm and 5–25‐cm depths, in three long‐term cropping experiments (7, 10 and 12 years) with and without ruminant grazing of cover crops. The three sites had contrasting soil and climatic char acteristics, but all sites were managed under no‐tillage, and treatments with livestock were managed with moderate grazing intensity. Ruminant grazing increased soil Na and P concentrations at 0–5‐cm depth, and increased Ca and Mg availability, base saturation and pH in deeper layers (5–25‐cm depth) or across the soil profile (0–25 cm). Land‐use complexity changed the soil exchangeable complex, resulting in soil acidity amelioration and consequently reduced Al toxicity, but it also had a negative impact on K saturation and cationic micronutrient availability (Zn, Mn, Cu and Fe). In general, grazing improved or did not change most soil chemical properties, and any negative effects of animal presence did not limit agroecosystem productivity. Therefore, under appropriate nutrient and grazing management, no‐tillage farming with integrated crop–livestock systems can uphold soil chemical conditions to sustain primary and secondary productivities in agroecosystems. Highlights Is the soil fertility in no‐tillage systems affected by ruminant grazing of cover crops? Land‐use complexity increased P, Na, Ca and Mg availability, and pH, and reduced Al toxicity Soil acidity amelioration decreased K saturation and cationic micronutrient availability Agriculture complexity under no‐tillage fosters soil fertility to allow sustainable intensification