[Effects of combined application of pig manure with urea on grain yield and nitrogen utilization efficiency in rice-wheat rotation system]. / çŒªç²ªé æ–½åŒ–è‚¥å¯¹ç¨»-éº¦è½®ä½œç³»ç»Ÿç±½ç²’äº§é‡å’Œæ°®ç´ åˆ©ç”¨çŽ‡çš„å½±å“.

To examine the effects of pig manure application on dry matter production, nitrogen accumulation and distribution, grain yield and nitrogen use efficiency of rice and wheat, the field trial was conducted with wheat 863 and rice 498. Fertilization treatments consisted of seven rates of organic manure supply: control (CK, no chemical nitrogen fertilizer, no pig manure), conventional fertilizing (T1, no pig manure), 2500 kg·hm-2 pig manure with 75% conventional fertilizing (T2), 5000 kg·hm-2 pig manure with 50% conventional fertilizing (T3), 10000 kg·hm-2 pig manure (T4), 15000 kg·hm-2 pig manure (T5) and 20000 kg·hm-2 pig manure (T6). Combined application of pig manure with chemical fertilizer promoted dry matter accumulation of rice and wheat throughout the growing season. At the maturity stage of rice and wheat, the highest aboveground dry matter accumulation presented under highest pig manure input (T6). The dry matter accumulation and nitrogen distribution were enriched in stem or leaf. The dry matter accumulation and nitrogen distribution rate in grain at T6 was significantly lower than T2 treatment. The high-est nitrogen fertilizer partial productivity, fertilizer agronomic efficiency and grain yield of rice pre-sented at T3 treatment, which increased by 11.4%, 55.4%, 11.4% than that of conventional chemical fertilizer treatment, respectively. These vaules for wheat were at T2, which was 14.0%, 29.1%, 14.0% higher than that of conventional fertilizer treatment, respectively. The combined application of pig manure with appropriate rates of chemical fertilizer (T2 and T3) could promote dry matter accumulation, the migration of nitrogen to grains, the increase of yield and the nitrogen use efficiency. Too much pig manure input (15000-20000 kg·hm-2) could lead to excessive supply of nitrogen for crops. In this case, the transportation of dry matter to economic organs would be blocked and the nitrogen enriched to stem. The late-maturing phenomenon occurred, resulting in significant decrease of grain yield.

[Effects of controlled release blend bulk urea on soil nitrogen and soil enzyme activity in wheat and rice fields]. / æŽ§é‡ŠæŽºæ··å°¿ç´ å¯¹ç¨»ã€éº¦åœŸå£¤æ°®ä¸Žé ¶æ´»æ€§çš„å½±å“.

A field experiment was conducted to investigate the effect of controlled-release fertilizer (CRF) combined with urea (UR) on the soil fertility and environment in wheat-rice rotation system. Changes in four forms of nitrogen (total nitrogen, ammonium nitrogen, nitrate nitrogen, and microbial biomass nitrogen) and in activities of three soil enzymes participating in nitrogen transformation (urease, protease, and nitrate reductase) were measured in seven fertilization treatments (no fertilization, routine fertilization, 10%CRF+90%UR, 20%CRF+80%UR, 40%CRF+60%UR, 80%CRF+20%UR, and 100%CRF). The results showed that soil total nitrogen was stable in the whole growth period of wheat and rice. There was no significant difference among the treatments of over 20% CRF in soil total nitrogen content of wheat and rice. The soil inorganic nitrogen content was increased dramatically in treatments of 40% or above CRF during the mid-late growing stages of wheat and rice. With the advance of the growth period, conventional fertilization significantly decreased soil microbial biomass nitrogen, but the treatments of 40% and above CRF increased the soil microbial biomass nitrogen significantly. The soil enzyme activities were increased with over 40% of CRF in the mid-late growing stage of wheat and rice. By increasing the CRF ratio, the soil protease activity and nitrate reductase activity were improved gradually, and peaked in 100% CRF. The treatments of above 20% CRF could decrease the urease activity in tillering stage of rice and delay the peak of ammonium nitrogen, which would benefit nitrogen loss reduction. The treatments of 40% and above CRF were beneficial to improving soil nitrogen supply and enhancing soil urease and protease activities, which could promote the effectiveness of nitrogen during the later growth stages of wheat and rice. The 100% CRF treatment improved the nitrate reductase activity significantly during the later stage of wheat and rice. Compared with the treatments of 40%-80% CRF, 100% CRF reduced the soil nitrate content of 20-40 cm soil layer in wheat significantly suggesting it could reduce the loss of nitrogen.