Manure collection and distribution on Wisconsin dairy farms

Manure management plans require knowing the amount of manure produced, collected, and available for land-spreading. Whereas much information is available to calculate manure production, little is known about the types and amounts of manure actually collected on typical dairy farms. This study of 54 representative Wisconsin dairy farms showed significant regional, housing, and herd size differences in collection of manure from lactating cows (Bos taurus), dry cows, and heifers. Significantly (P < 0.05) less manure is collected in the hilly southwest (56% of total annual herd production) than in the undulating south central (72%) or the flat northeast (68%) regions. Collection of lactating cow manure is significantly (P < 0.05) lower from stanchion (66% of total annual production) than free-stall (89%) housing, and significant (P < 0.05) positive relationships were found between the number of lactating cows a farm keeps and the percentage manure collected. Average annual manure N (range of 116-846 kg N ha(-1)) and P (range of 24-158 kg P ha(-1)) loading rates in areas where manure goes uncollected was highest in unvegetated barnyards followed by vegetated and partially vegetated outside areas. Once uncollected manure was accounted for, average annual loading rates on cereal cropland ranged from 128 to 337 kg ha(-1) of manure N, and from 45 to 139 kg ha(-1) of manure P. Compared with adjacent cropland, the accumulation of uncollected manure has vastly increased soil test P, K, and organic matter levels in outside areas. Manure management on Wisconsin dairy farms with small to medium herds might require assistance in managing manure in outside confinement areas to reduce the risk of impairing surface and ground water quality.