Time and methods of liquid dairy manure application for nitrogen utilization in corn silage production

Two field experiments were conducted at the Dairy Experiment Station, Lewisburg, TN, (i) to investigate inject versus broadcast application of liquid dairy manure both in the fall and spring as a source of nitrogen (N) for corn silage (Zea mays L.) production (Experiment 1), and (ii) to investigate the usefulness of a nitrification inhibitor [N-Serve, (nitrapyrin, 2-chloro-6-trichloromethyl pyridine)] in conserving manorial N applied through broadcasting and injecting in the fall (Experiment 2). Liquid dairy manure obtained from a pit receiving milking parlor wastes was applied in approximately equal amounts by weight to all manure treatments (~68 Mg * ha^-1 in Experiment 1 and ~90 Mg * ha^-1 in Experiment 2); inorganic fertilizer treatments received 134 kg N * ha^-1 as NH₄NO₃. Nitrapyrin treatments in Experiment 2 received N-Serve either as a tank mix calculated to give 4.7 L * ha^-1 of the active ingredient (manure treatments) or as a broadcast application (inorganic N treatment). Each load of manure was sampled in the field prior to application. Grain and silage yields and tissue samples were collected from each plot, and soils were sampled in the fall of each year following corn harvest and prior to fall application of manure.

Times and methods of manure application had no influence on silage or grain yields, silage nutrient content, or soil test extractable nutrients in 1981-1982 (Experiment 1). This was probably because of the high fertility status of the experimental area from prior manure application.

There was no effect of N-Serve on silage or grain yield, silage nutrient content or soil test extractable nutrients (Experiment 2), possibly because dry weather and soil temperature affected the response to N-Serve. In the second experiment, the inject application resulted in higher yields than broadcast application of manure, and conventional fertilization resulted in higher yields than did manure application. In this experiment manure application resulted in higher concentrations of phosphorus (P) and potassium (K) in silage than did conventional fertilization.