THE AVAILABILITY OF THE NITROGEN IN FARM MANURE UNDER FIELD CONDITIONS

Abstract

A field study of the availability of the N in cattle manure for spring barley. The amount of N recovered in the barley is never greater than the amount of ammonia or liquid-manure N applied. Little if any of the water-insoluble N is recovered in the 1st crop. Complete manure turned under immediately on spreading gives a recovery of 80% of the urea or ammonia N which it contains. Fresh manure, and manure fermented in storage, give similar recoveries when plowed under immediately on spreading. Top dressing and disking in gave higher availabilities than when the manure is plowed down. There are losses of the liquid-manure N when the manure is allowed to dry after spreading. Manure which has only ammonified gives the greatest loss, completely fermented manure a lesser loss, and fresh manure, the least loss on drying. Spreading manure during rainy weather reduces losses. Straw in manure lowers the N recovery in the 1st crop. 6% of straw in the manure reduces the N recovery more than 20%.