N Release from Livestock Waste Compost Pellets in Barley Fields

N release patterns from dairy cattle, swine, and poultry waste compost pellets were studied using the buried glass filter paper method in barley fields. Field experiments with barley were also carried out to study the relationship between N release from pellets and N absorption by barley. Results showed that about 28,36,and 44% of N were released from 3 types of compost pellets throughout the growth stages of barley, respectively. However, since more than 60% of N was released before the tillering stage of barley, barley absorded a large amount of N and grew excessively in winter. When poultry and swine waste compost pellets were incorporated into dairy cattle waste compost at the N ratio of 1 : 1 or 2 : 1,N release rate from the incorporated pellets decreased, but N was still mainly released at early stage after application. Compost pellets made of dairy cattle and swine waste compost at the N ratio of 1 : 1 led to the highest production of barley in this experiment, followed by compost pellets made of dairy cattle and poultry waste compost at the N ratio of 1 : 1 and poultry waste compost pellets. The use of these three types of pellets resulted in a barely yield higher than that obtained with chemical fertilizers at the significant level of 1%. Amounts of P and K absorbed by barley in the pellet treatments exceeded those in the chemical fertilizer treatments, suggesting that additional application of chemical fertilizer containing phosphorus and potassium was not necessary when animal waste compost was used for barley production as basal fertilizer. Meanwhile, the balance of nutrients, such as N, P, and K, in the compost pellets should be considered also to achieve comprehensive management of nutrients for crop production.