Effect of Compost versus Animal Manure Fertilization on Crop Development, Yield and Nitrogen Residue in the Organic Cultivation of Potatoes

Summary

Organic farmers in Flanders use manure from extensive conventional livestock systems due to a lack of animal manure from organic producers. The research question was if on-farm prepared compost mainly consisting of vegetal residues can be a good alternative. A long-term fertilization trial with a 4-year crop rotation of maize - potatoes - spring barley - red clover is carried out on two fields with a time difference of one year. The fertilization treatments are on-farm prepared compost, applied as a single dose and a double dose, farmyard manure, slurry and slurry combined with composted municipal waste. This paper concerns the experimental results of the potato crop in 2006 and 2007. The nitrate content of the plant juice was monitored and the potato yield and nitrate content in the soil profile at the end of the growing season were determined. In 2006 the potato yields were significantly higher for both farm compost treatments while the nitrate residues in soil were significantly lower. The early, high and constant leaf blight disease pressure in 2007 resulted in lower yields and less marked treatment effects. This investigation demonstrated that application of mature compost can result in a faster development of the potato crop in the first weeks of the growing season, which is important for sufficient yields in organic potato growing.