控释氮肥比例对土壤氮含量和玉米氮素吸收利用的影响

通过大田试验,研究相同氮肥施用量的条件下,不同比例控释尿素与普通尿素混合施用对土壤氮含量、玉米植株氮素吸收利用及产量的影响。结果表明:施氮显著提高了0-20,20-40cm耕层土壤碱解氮和全氮含量。全施普通尿素时,一次施肥可提高前期土壤氮含量,而2次施肥则有利于提高后期土壤氮含量;与普通尿素施肥相比,掺混一定比例的控释尿素一次性底施可显著提高各生育时期耕层土壤含氮量。适宜比例的控释尿素与普通尿素掺混施用可在一定程度上增加玉米中后期的氮素积累量,提高氮肥表观利用率、氮肥农学效率和肥料贡献率以及玉米功能叶关键酶活性,在相同氮肥水平下,其一次性底施的效果甚至超过普通尿素2次施用。随控释尿素比例的增加,玉米产量呈先增后减趋势,以75%控释尿素+25%普通尿素处理产量最高,比普通尿素一次施增产12.09%(2014年)和21.58%(2015年),比普通尿素2次施肥增产8.27%(2014年)和14.19%(2015年)。因此,普通尿素掺混75%比例的控释尿素进行一次底施,不仅能够协调在整个玉米生育期土壤对氮素的供应,实现玉米的有效增产,而且还能够减少施肥次数和劳力投入。

Effects of the Mixed Ratios of Controlled-Release Nitrogen Fertilizer on Soil Nitrogen Content and Its Uptake and Utilization of Maize

A field experiment was carried out to study the effects of different mixed ratios of controlled-release urea (CRU) and conventional urea (CU) on soil nitrogen content, its uptake and utilization of maize (Zea mays L.) and grain yield. All treatments were applied with the same rate of nitrogen. The results showed that nitrogen fertilization significantly increased soil available nitrogen and total nitrogen contents in tillage layers of 0-20 cm and 20-40 cm. When using conventional urea, single basal application increased soil nitrogen content in the early growth stage, while twice application could improve the nitrogen content in the late growth stage. Compared with the conventional urea application, the single basal application of urea with a certain proportion of controlled-release urea significantly improved soil nitrogen content in tillage layer in each growth period. The suitable proportion of controlled-release urea mixed with conventional urea increased the nitrogen accumulation in maize in the middle and later stages to some extent, improved the apparent utilization rate of nitrogen fertilizer, the efficiency of nitrogen fertilizer, fertilizer contribution and the key enzymes activities of nitrogen metabolism in function leaves. At the same nitrogen application rate, the effect of the single basal application of the mixed fertilizers was even better than the twice applications of conventional urea. With the increasing proportions of controlled-release urea, the maize yield first increased and then decreased, and the yield under the treatment of 75% controlled-release urea+25% conventional urea was the highest, which was 12.09% (2014) and 21.58% (2015) higher than single basal application of conventional urea fertilizer, 8.27% (2014) and 14.19% (2015) higher than the twice fertilizations, respectively. Therefore, the conventional urea mixed with 75% controlled-release urea could not only harmonize the soil nitrogen supply throughout the maize growing period, but also reduce the times of fertilization, and consequently cut the labor input.