农业N肥投入与生态经济效益的协调增长

精细养分管理多年的试验结果证明水稻养分投入至少可以比目前减少25％，而产量可上升8％，同时每公顷可以降低淋溶量和气化量近30％。利用TechnoGIH模型计算养分利用效率，其结果表明：目前水稻N的表观吸收利用率仅达到0．2，而采用精细养分管理可提高到0．3，如果采用更先进的技术可以将其提高到0．4，甚至0．5～0．6。而目前对于非稻类作物蔬菜，N的表观吸收利用率仅为0．14。如果改进技术将其提高到0．20，N肥的投入可以减少32％，N的丧失可以减少29％。如果能进一步提高到0．25，至少还可以减少14％的N投入和16％的N丧失。这样淋溶和气化对环境产生的影响可大大降低，从而避免过多的养分通过淋溶渗入土壤和直接挥发到大气中，影响生态环境，影响农业投入产出效益。因此，需要从经济收益、环境效益、社会效益等多方面综合考虑未来农业生态效益协调增长方式。

Research on harmonious growth of eco-economy and agricultural N input

In recent experiments researchers have succeeded in increasing the ANRE (Apparent nitrogen-recovery efficiency)in double rice from 0.2 kg plant N kg -1 fertilizer N in the farmer's fertilizer practice to 0.3 kg kg -1 using site-specific nutrient management (SSNM). Despite these recent technological developments, there is still space for improving N-use efficiency in rice. Apparent recovery rates of SSNM are 0.3 kg plant N kg -1 fertilizer N, while with good management it is possible to achieve rates of 0.5-0.6 in irrigated rice. These rates could be reached through an even more real-time N management. We computed nitrogen requirements and losses for apparent N-recovery rates of 0.4 and 0.5 to gain insight of the consequences of the development and adoption of such technologies for environmental sustainability. The results show that a lot can be gained from these technologies. An increase of the apparent N-recovery of 0.3 to 0.4 results in a decrease in total nitrogen losses of 32 percent for double rice and 25 percent for single rice. A further increase to 0.5 would result in another decrease of 14 and 16 percent points for double and single rice, respectively. Fertilizer recovery rates are even lower for horticultural production than for rice. we used TechnoGIN to compute potential technologies for the common rotation of greens-celery-rice. We increased the ANRE from 0.14 in farmer practice to 0.20 and 0.25 assuming that yields remain the same. Like SSNM techniques in rice,these changes could be achieved by fine-tuning fertilizer gifts to crop requirements. The results of our computations are promising: An increase of the ANRE from 0.14 to 0.20 would result in a decrease in nitrogen fertilizer of 32 percent and a decrease in nitrogen losses of 29 percent. A consecutive increase of the ANRE to 0.25 would imply another decrease in nitrogen costs by 14 percent points and nitrogen losses by 16 percent points. These computations indicate that there is ample scope for the introduction of new technologies that are beneficial for farmer income as well as the environment.