Soil Properties under Nitrogen‐ vs. Phosphorus‐Based Manure and Compost Management of Corn

Abstract

Core Ideas Annual application of manure to corn at P‐removal based rates will reduce P buildup over time. Lowering manure and compost rates over time will impact SOM. Tillage‐based incorporation of manure at lower rates will aid in N conservation but impact SOM buildup. Concerns about P enrichment of soil, streams, and lakes, NH3 emissions from surface‐applied manure, and increasing N fertilizer costs have resulted in greater adoption of manure incorporation at rates that approximate P removal. A 5‐yr field study was conducted comparing the influence of annual spring applications of N‐ vs. P‐removal‐based compost (74 and 46 Mg ha−1 wet basis, respectively), liquid dairy manure (196 and 68 kL ha−1, respectively), and sidedress N fertilizer (0 and 112 kg ha−1) on soil pH, soil organic matter (SOM), respiration, NO3–N, and soil test P (STP) and K (STK) in a corn (Zea mays L.) silage cropping system on a calcareous central New York soil. Manure was incorporated with tillage in the P‐removal‐based system. After 5 yr, soil pH (0–20 cm) remained unchanged compared with its initial level in 2001 regardless of the application rate or source. In P‐based manure and inorganic N plots, SOM declined with time but increased by 4 g kg−1 with N‐based compost. Solvita CO2 respiration increased only for N‐based compost (41 g mg−1), which was greater than for P‐based manure (32 g mg−1) in April 2005. After 5 yr, topsoil (0–20 cm) STP and STK were greatest with N‐based compost and manure. These results show the benefits of compost application for SOM accumulation and respiration, the benefits of P‐based applications for management of STP and STK, and the negative impact on SOM because of tillage incorporation of manure at P‐based rates. Manure injection rather than tillage‐based incorporation might counteract this negative impact.