Conservation tillage is compatible with manure injection in corn silage systems

Adoption of conservation tillage practices has increased over the past 30 yr in the United States. Research is needed to evaluate if reduced tillage practices are compatible with manure injection on dairy farms. Two corn (Zea mays L.) silage studies were conducted in New York to evaluate the impact of zone tillage depth and tillage intensity on early plant growth and soil nitrate-N, corn silage productivity and quality, and nutrient uptake at harvest. Treatments included three zone tillage depths (0, 18, and 36 cm; with aerator seedbed preparation) for Study 1 (2012-2013) and three tillage intensities (no tillage, reduced tillage [aerator seedbed preparation without zone tillage], and intensified reduced tillage [aerator seedbed preparation plus zone tillage at 18-cm depth]) for Study 2 (2014-2016). Manure was injected in the spring, and all fields had a manure and zone tillage history. Zone tillage depth did not affect early plant growth, soil nitrate-N content at V5-V6, corn silage yield, quality, corn stalk nitrate test (CSNT)-N, or nutrient removal with harvest. The CSNT-N levels exceeded 2,000 mg NO3-N kg(-1), confirming sufficient N for each treatment. Study 2 showed no impact of tillage intensity on corn growth, yield, or nutritive value, and CSNT-N levels always exceeded 2,000 mg NO3-N kg(-1). These findings show that, on fields with a history of manure addition and reduced tillage, manure injection followed by planting without further seedbed preparation or zone tillage can maintain yields and quality and can conserve N while reducing soil disturbance and tillage-associated fuel, equipment, and labor costs.