Managing Manure in Potato and Vegetable Systems

manure over a larger land base can contribute to higher soil productivity. Role of manure Maintaining and improving soil quality in veg-etable and potato systems is a difficult task. Heavy equipment can cause compaction, crop residues tend to be minimal in these rotations, and sandy soils generally have low organic mat-ter levels. Degraded soils can be revitalized by adding manure or compost. To minimize costs while enhancing organic inputs, a combination of manure and cover crops is recommended to rebuild soils. Both short-term yield benefits and long-term soil building can occur through the addition of organic matter. Recent studies in Michigan sug-gest that application of poultry manure with a reduced fertilizer rate can enhance potato tuber yields by 30 to 60 cwt/acre at some sites (Figures 2 and 3). The mechanism is under study but may be related to any of the following: enhance-ment of soil microbial activity, the active organic matter fraction or enhanced nutrient supply. Figure 2. Chip potato response to 160 lb N/acre fertil-izer plus 5,000 lb/acre aged poultry manure, supply-ing about 40 lb N/acre. The soil was left bare in the winter or a rye cover crop was used. (J. Nyiraneza and S. Snapp, unpublished data.) Other benefits take time to accrue and are gen-erally associated with manures that contain large amounts of organic materials, such as dairy manure or manure from straw-bedded live-stock. Soil quality benefits include increased water-holding capacity, improved soil structur