Solid manure distribution by rear- and side-delivery spreaders

Manure distribution across the application swath of a spreader needs to be relatively uniform to take full advantage of fertilizer nutrients in solid manure. A series of field experiments measured application uniformity across the swath and in the travel direction for two rear- and one side-delivery manure spreaders using solid beef or dairy manure. Uniformity of overlapped patterns at various swath widths was calculated from field data. For the rear-delivery spreaders, apron speed affected the application rate and at times the distribution uniformity, as measured by coefficient of variation (CV). Increasing apron speed usually increased application rate and at times increased distribution uniformity. Uniformity was similar for both one- and two-beater rear-delivery spread patterns. Load phase (beginning, middle, and end of a load) had little effect on the distribution of the manure across the swath. With the side-delivery spreader, a full gate opening tended to improve across-swath uniformity as compared to a half gate opening. A deflector on the side-delivery spreader placed in mid-position improved across-swath uniformity during fall applications with drier manure; however, deflector position had no effect on uniformity in a spring experiment. Application uniformity across the swath was worse than in the travel direction, particularly for the rear-delivery spreader, unless the swaths were carefully overlapped. High across-swath CVs were usually lowered when spread patterns were overlapped, although the amount of overlap required to maximize uniformity may be impractical. Application and uniformity graphs generated from field data can be useful in predicting the uniformity of the spread pattern for a swath width selected to provide a given application rate.