Opportunities to decrease the water quality impact of spring forage crops on dairy farms

Abstract

Currently spring forage crops are used to manage late calving cows on the dairy platform, protect spring pasture from pugging damage, and allow the animals to feed on a mix of brassica and pasture to transition to a pasture-based diet. In addition, like winter forage crops, they could contribute considerable water quality contaminants via surface runoff. However, it may be possible to manage farms without spring forage crops. Two Southland dairy farms were used to show: 1) flowweighted mean concentrations of many water quality contaminants in surface runoff from a spring-grazed forage crop were similar to those found in studies of winter-grazed forage crops; and 2) that, using growth rate data for 2007-2012, in no year was the modelled forage crop beneficial from a feed supply perspective, and in all years the farms had similar financial performances and fewer feed deficits under all-grass management. Hence, good pasture management (e.g. avoiding treading damage using a stand-off pad and short grazing times) may negate the need for a spring forage crop, decreasing contaminant losses while not impairing farm profitability. Keywords: surface runoff, transition diet, water quality, winter forage crop.