[Long-term trial on fertilization and on use of recycled nutrients in farming systems V. Response of crop yields to fertilization in different precipitation years and estimates of water and nutrient interaction].

According to the responses of crop yields under fertilizations in 1996 with normal precipitation (456 mm in crop growth season) and in 1998 with higher precipitation (598 mm in growth season), the effect of water and nutrient interaction on crop yields in semihumid-semiarid region of west Liaoning Province were estimated. Under N application and sufficient water supply (more rainfall), the increase of crop yields was 3,056 kg.hm-2, of which, 1,996 kg.hm-2 was estimated from water-nutrient interaction, while in NP and compost treatment with sufficient water supply, the yield increase was 4,703 kg.hm-2, of which, 1,554 kg.hm-2 was estimated from water-nutrient interaction.

[A long-term field trial on fertilization and on use of recycled nutrients in farming systems III. Recycling rate of P and N through a composting cycle and recoveries of P and N in organic manure].

The results from a nine years experiment indicated that the average loss rate of N and P contained in harvest products through a feeding-composting cycle was about 30%. Under high yield conditions, the amount of recycled N and P from 60% of harvested products and through a composting cycle in a farming system were about 55-70 kg.hm-2 and 9-11 kg.hm-2, respectively, equivalent to 37%-47% of N and 36%-44% of P from fertilizers applied every year to the system.