[Application effects of fertilizer recommendation by Nutrient Expert System on radish]. / å »åˆ†ä¸“å®¶ç³»ç»ŸæŽ¨èæ–½è‚¥åœ¨èåœä¸Šçš„åº”ç”¨æ•ˆæžœ.

A field experiment was conducted for two seasons to evaluate the application effects of a decision support system named Nutrient Expert on radish based on yield response and agronomic efficiency, to provide theoretical and technical support for convenient and quick recommendation on fertilization management. There were seven treatments: farmer's practice treatment (FP), recommended fertilization treatment based on Nutrient Expert (TE), recommended fertilization treatment based on soil testing (TS), treatment of replacing 30% nitrogen fertilizer with organic fertilizer based on TE (TE+OM), and corresponding nitrogen omission treatment (TE-N), phosphorus omission treatment (TE-P), and potassium omission treatment (TE-K). We measured and compared the effects of different fertilization managements on radish yield, nutrient uptake, fertilizer utilization and fertilization benefit. The results showed that the N, P2O5 and K2O fertilizer applications based on Nutrient Expert were 200, 132 and 215 kg·hm-2 in the first half of the year, and 171, 204 and 251 kg·hm-2 in the second half of the year, respectively. The Nutrient Expert recommended fertilization adjusted the application amount of nitrogen, phosphorus, and potassium fertilizer. Compared with FP treatment, the economic yield of radish in the two-season experiments increased by 14.8% and 18.4%, and the profit of fertilization increased by 20115 and 14905 yuan·hm-2, respectively. Compared with the TS treatment, the economic yield of radish over the two seasons increased by 9.8% and 16.8%, and the profit of fertilization increased by 9076 and 9987 yuan·hm-2, respectively. The Nutrient Expert recommended fertilization improved the agronomic efficiency and nutrient recovery efficiency of radish, and promoted the efficient utilization of nutrients. The reasonable proportion of organic fertilizer in radish production could promote the transfer of plant nutrients to roots to a certain extent. In general, the application of Nutrient Expert on radish was feasible. This method could make full use of the indigenous nutrients of soil, consider the balance and sustainable supply, and reasonably regulate the supply of nitrogen, phosphorus and potassium, and finally result in high yield, high efficiency and sustainable development of radish production.

[Emission of NH3 and N2O from Spinach Field Treated with Different Fertilizers].

Agricultural management techniques such as fertilizer or manure application have substantial influence on NH3 and N2O emissions and, by understanding this influence, management strategies can be developed to reduce them. An experiment was conducted in a greenhouse at Hunan Agricultural University during 2012 to 2013, to investigate effects of different fertilizers on NH3 and N2O emissions. The treatments included control without fertilizer (CK), swine composting fertilizer (SC), stored swine manure fertilizer (SS), and chemical fertilizer (FC). The fluxes of NH3 and N2O were collected by venting method and static-chamber method, respectively. The results showed that during the spinach growth season, compared with FC, loss of both NH3 and N2O for SC were reduced by 52.9% and 95.12%, respectively(P<0.01). However, loss of NH3 for SS increased by 24.8%, and loss of N2O reduced by 48.8% compared with FC. Loss rate of NH3 were SS (10.97%) > FC (4.19%) > SC(2.74%), and emission coefficient for N2O were FC(4.50%) > SC(2.21%) > SS(0.60%). Yield and utilization of nitrogen for SC were reduced by 19.61% and 13.20% compared with FC, respectively, but not significantly; and significantly reduced by 27.9% and 40.0% compared with SS, respectively. Loss of gases (NH3 and N2O) for SC were 1.83%, which was the lowest, while utilization of nitrogen for SC was 13.20%, similar with FC. Greenhouse temperature was not the critical factor during the spinach planting in winter, but soil water was. Therefore, optimizing manure management could reduce ammonia volatilization and N2O emission loss without decreasing vegetables production, and the present data indicated that SC would be optimal for better yields with reduced ammonia volatilization and N2O emission loss.