[Effects of coated controlled release urea combined with conventional urea on winter wheat growth and soil NO3- -N].

Field experiments were conducted to study the effects of different dosages coated controlled release urea (PCU60, 60 d release duration) combined with conventional urea (U) used as basal on the winter wheat grain yield, nitrogen (N) recovery rate, and soil NO3- -N content, etc. Five treatments were installed, i.e., U (CK), 10% PCU60+90% U (PU1), 20% PCU60+80% U (PU2), 30% PCU60+70% U (PU3), and 40% PCU60+60% U (PU4). In the meantime, a comparative analysis was also carried out on the PCU60 N release characteristics under field condition and in 25 "C static water. At the same N dosage, all the test indices in treatment PU4 were significantly higher, with the grain yield, N recovery rate, total N accumulation amount, total tiller number and aboveground biomass at ripening stage, and economic benefit increased by 5.6%, 14.6%, 7.2%, 2.6%, 7.5%, and 984.3 yuan x hm(-2), respectively, compared with those in treatment U. The accumulation amount of NO3- -N in 0-100 cm soil layer in all treatments ranged in 39.70-49.93 kg x hm-2, and was the lowest (39.70 kg x hm(-2)) in treatment PU4. The N release pattern of PCU60 under field condition better fitted the N absorption characteristics of winter wheat.

[Development and evaluation of fertilizers cemented and coated with organic-inorganic materials].

Four kinds of organic-inorganic cementing and coating materials were prepared by a coating method using water as the solvent, and the corresponding cemented and coated fertilizers (B2, PS, F2, and F2F) were produced by disc pelletizer. The tests on the properties of these fertilizers showed that the granulation rate, compression strength, and film-forming rate were B2 > PS > F2 > F2F. Soil column leaching experiment showed that the curve of accumulated nitrogen-dissolving rate was the gentlest for B2. In 48 days, the accumulated nitrogen-dissolving rate was in the order of B2, 54.65% < PS, 56.16% < F2, 59.47%, < F2F, 63.12%. Field experiment showed that compared with the same application amount of NPK, all the test fertilizers had better effects on corn yield, among which, B2 was the best, with the corn yield and fertilizer use efficiency increased by 19.72% and 20.30%, respectively. The yield-increasing effect of other test fertilizers was in the order of PS > F2 > F2F.