Management Drives Differences in Nutrient Dynamics in Conventional and Organic Four-Year Crop Rotation Systems

Abstract

Application of exogenous N fertilizers provides agronomic benefits but carries environmental liabilities. Managing benefits and liabilities of N-based fertilizers in conventional (CNV) and organic (ORG) cropping systems might be improved with better knowledge of nutrient dynamics, the generation of intrinsic N, and maintenance of soil organic matter. This study evaluated mineral N dynamics, yields, residue inputs, and change in soil organic C (SOC) and total N (TN) in strip-tilled, four-year crop rotations [corn (Zea mays L.)-soybean (Glycine max [L.] Merr.)-wheat under-seeded with alfalfa (Triticum aestivum L./Medicago sativa L.)-alfalfa] over eight years of production under CNV management using mineral-N (NO3NH4) and chemical pesticides or ORG management using organic-N (animal manure) and no chemical treatments. In ORG, N availability increased over time, but did not benefit ORG yields due to poor control of insects and weeds. Corn, soybean, and wheat grain yields were 1.9 to 2.7 times greater in CNV. In general, SOC was lost in CNV but did not change in ORG. Cumulative yield N removals exceeded cumulative fertilizer-N inputs by an average of 78% in CNV and 64% in ORG. These results indicated ORG management supported N availability by generating intrinsic N.

Soil Nitrate Nitrogen Content and Grain Yields of Organically Grown Cereals as Affected by a Strip Tillage and Forage Legume Intercropping

“…The addition of plant residues from green manure and their incorporation into soil activates the subsequent physico-chemical protection of organic carbon [ 48 ]. Prolonged application of no-tillage and the accumulation of organic matter of different availability in the soil increases the soil’s capacity to supply available nitrogen by generating intrinsic resources [ 49 ]. This contributes to an improvement in plant nutrition with nitrogen in the long run.…”

Patterns of Nutrient Dynamics within and below the Rootzone of Collard Greens Grown under Different Organic Amendment Types and Rates

“…Kebrom et al [26] identified phytotoxic levels of copper and nickel in commercial organic soil amendments recycled from poultry farms and municipal wastes and found that commercial chicken manure and Milorganite (recycled from municipal waste) were more phytotoxic than poultry manure. Application of exogenous N fertilizers (poultry or chicken manure and/or biosolids such as Milorganite) provides agronomic benefits but carries environmental liabilities [30]. For example, higher cumulative CO 2 emissions for the soils amended with chicken manure and Milorganite but the lowest for the soils amended with dairy manure were reported by Ray et al [31].…”