Effects of Site-Specific Nitrogen Management on Yield and Dry Matter Accumulation of Rice from Cold Areas of Northeastern China

The effects of yield increase and mechanism of site-specific nitrogen management （SSNM） in five rice varieties from cold areas of northeastern China were studied. Plot experiment for critical SPAD value and experiments of two fertilization methods, SSNM and farmer＇s fertilization practice （FFP） were conducted to study their effects on the quality and dry matter accumulation of rice population, as well as N uptake. Compared with FFP, SSNM significantly decreased the average N rate by 33.8%, significantly increased average ear-bearing tiller rate and LAI for grain-filling stage by 12.3% and 14.1-27.6%, correspondingly, improved dry matter weight and N uptake after heading period by 4.3-29.1% and 11.8-55.1% （P 〈 0.05）, and heightened recovery efficiency and agronomic efficiency by 38.5-133.4% （P 〈 0.05） and 39.8-194.3% （P 〈 0.05）, respectively, as well as increased the average yield by 9.8% in 2004 and 2005. The results indicated that the accumulation rate of dry matter and N increased the rice yield and N use efficiency, because of improving rice population quality and increasing LAI after heading period.

An integrated approach to site-specific management zone delineation

Dividing fields into a few relatively homogeneous management zones(MZs) is a practical and costeffective approach to precision agriculture. There are three basic approaches to MZ delineation using soil and/or landscape properties, yield information, and both sources of information. The objective of this study is to propose an integrated approach to delineating site-specific MZ using relative elevation, organic matter, slope, electrical conductivity, yield spatial trend map, and yield temporal stability map(ROSE-YSTTS) and evaluate it against two other approaches using only soil and landscape information(ROSE) or clustering multiple year yield maps(CMYYM). The study was carried out on two no-till corn-soybean rotation fields in eastern Illinois, USA. Two years of nitrogen(N) rate experiments were conducted in Field B to evaluate the delineated MZs for site-specific N management. It was found that in general the ROSE approach was least effective in accounting for crop yield variability(8.0%–9.8%), while the CMYYM approach was least effective in accounting for soil and landscape(8.9%–38.1%), and soil nutrient and pH variability(9.4%–14.5%). The integrated ROSE-YSTTS approach was reasonably effective in accounting for the three sources of variability(38.6%–48.9%, 16.1%–17.3% and 13.2%–18.7% for soil and landscape, nutrient and pH, and yield variability, respectively), being either the best or second best approach. It was also found that the ROSE-YSTTS approach was effective in defining zones with high,medium and low economically optimum N rates. It is concluded that the integrated ROSE-YSTTS approach combining soil, landscape and yield spatial-temporal variability information can overcome the weaknesses of approaches using only soil, landscape or yield information,and is more robust for MZ delineation. It also has the potential for site-specific N management for improved economic returns. More studies are needed to further evaluate their appropriateness for precision N and crop management.

水稻实地氮肥管理的氮肥利用效率及其生理原因

以代表性品种为材料,研究了水稻实地氮肥管理(SSNM)的氮肥利用效率及其生理机制。结果表明,SSNM的施氮量较常规施肥方法(FFP)降低了48.1%～63.0%,产量提高了0.1%～9.3%。SSNM的氮肥吸收利用率和农学利用率分别较FFP提高了31.4%～56.8%和143.6%～166.0%。水稻氮吸收高峰出现在穗分化期至抽穗期,此阶段SSNM处理氮的吸收量和其占最终总吸收量的比例均明显高于FFP。抽穗后SSNM水稻的吸氮量也明显高于FFP。自幼穗分化期开始,SSNM水稻根系重量和根系活力(尤其是单茎占有的根系活性)逐步超过FFP。SSNM明显提高了幼穗分化期和抽穗期水稻叶片中谷氨酰胺合成酶、硝酸还原酶和Fd-谷氨酸合酶的活性。抽穗后SSNM处理水稻剑叶的光合速率高于FFP,上述结果表明SSNM有利于促进水稻中后期根系生长,提高物质生产和养分吸收,从而提高氮肥的利用效率。

寒地稻田施氮状况与氮素调控对水稻投入和产出的影响

文章通过对黑龙江省1～3积温带240个农户的施肥情况调查,以及对试验区水稻氮素收支状况分析,研究了黑龙江省稻田土壤氮循环规律。结果表明,寒地稻田化肥投入氮量平均为150 kg.hm-2,占投入总量的72.4%,而且90%以上作基蘖肥施用,近60%的稻田氮素用量过高,稻田氮有17.2%的盈余,氮肥利用率较低。针对寒地水稻施氮问题,提出进行实地氮肥管理的策略,经过3年9个点次田间对比试验,证明该技术能降低氮肥用量30%以上,水稻产量增加10%以上,每公顷增收1 450元。

节水灌溉稻田水肥调控技术试验研究

水和肥是制约水稻生长的重要因素,合理的灌溉和施肥有利于提高水肥利用效率和减轻农田面源污染。根据田间试验资料,分析了不同灌溉和施肥方式对水稻产量和水肥利用效率的影响。结果表明,与淹水灌溉相比,控制灌溉水稻节水45.9%,减产7.8%,水分利用效率提高了6.3%~79.8%,群体水平和产量水平下达到显著差异,氮肥利用率增加5.2%~38.4%。与农民习惯施肥相比,实地氮肥管理和控释肥水稻施氮量减少59.8%和55.4%,减产2.4%和13.7%,氮肥利用率增加40.8%~70.8%,叶片水平和群体水平下水分利用效率提高了4.8%~22.8%。水肥综合调控表明,控制灌溉和实地氮肥管理可以作为节水、控污、高效的稻田水肥管理措施。

Recent Advances on the Technologies to Increase Fertilizer Use Efficiency

To increase fertilizer use efficiency （FUE） and to minimize its negative impact on environment have been the focal points in the world for a long time. It is very important to increase FUE in China for its relatively low FUE and serious losses of nutrients. Recent advances of the technologies to increase FUE are reviewed in this article. These include site-specific and real-time nitrogen management, non-destructive quick test of the nitrogen status of plants, new types of slow release and controlled release fertilizers, site-specific nutrient management, and use of urease inhibitor and nitrification inhibitor to decrease nitrogen losses. Future outlook in technologies related to FUE improvement is also discussed.

Changes in Grain Yield of Rice and Emission of Greenhouse Gases from Paddy Fields after Application of Organic Fertilizers Made from Maize Straw

A field experiment was conducted at the farm of Yangzhou University, Yangzhou, China, to study the effects of organic fertilizers made from maize straw on rice grain yield and the emission of greenhouse gases. Four organic fertilizer treatments were as follows： maize straw （MS）, compost made from maize straw （MC）, methane-generating maize residue （MR）, and black carbon made from maize straw （BC）. These organic fertilizers were applied separately to paddy fields before rice transplanting. No organic fertilizer was applied to the control （CK）. The effects of each organic fertilizer on rice grain yield and emission of greenhouse gases were investigated under two conditions, namely, no nitrogen （N） application （ON） and site-specific N management （SSNM）. Rice grain yields were significantly higher in the MS, MC and MR treatments than those in CK under either ON or SSNM. The MS treatment resulted in the highest grain yield and agronomic N use efficiency. However, no significant difference was observed for these parameters between the BC treatment and CK. The changes in the emissions of methane （CH4） carbon dioxide （CO2）, or nitrous oxide （N20） from the fields were similar among all organic fertilizer treatments during the entire rice growing season. The application of each organic fertilizer significantly increased the emission of each greenhouse gas （except N20 emission in the BC treatment） and global warming potential （GWP）. Emissions of all the greenhouse gases and GWP increased under the same organic fertilizer treatment in the presence of N fertilizer, whereas GWP per unit grain yield decreased. The results indicate that the application of organic fertilizer （MS, MC or MR） could increase grain yield, but also could enhance the emissions of greenhouse gases from paddy fields. High grain yield and environmental efficiency could be achieved by applying SSNM with MR.

实地氮肥管理对氮肥利用率及稻米品质的影响

以牡丹江地区代表性品种牡丹江28和空育131为材料,研究了水稻实地氮肥管理(SSNM)的氮肥利用效率及其对稻米品质的影响。结果表明,SSNM的施氮量较常规施肥方法(FFP)降低了54.2%～61.5%,产量提高了1.6%～8.6%。SSNM的氮肥吸收利用率和农学利用率分别较FFP提高了42.7%～72.9%和132.1%～242.5%。此外,实地氮肥管理提高了稻米的加工品质,还明显降低了直链淀粉含量,提高了胶稠度,降低了糊化温度和蛋白质含量,改善了稻米的食味品质。

太湖流域稻田不同氮肥管理模式下的氮素平衡特征及环境效应评价

研究了不同氮肥管理模式下的稻田氮素平衡特征和环境效应.在太湖主要入湖河流直湖港下游开展了农户常规施肥处理、缓控释肥处理、有机无机肥配施处理、按需施肥处理以及化肥减量优化处理5种氮肥管理模式的田间小区试验,实测了稻季的径流和淋洗氮损失,估算了氨挥发和N2O等气体损失,分析了不同氮肥处理下的环境排放量和氮素平衡特征.与农户常规施肥处理相比,其他处理在减少氮肥总投入量20%～40%的情况下产量与农户对照基本持平,氮肥利用率提高了14.5%～44%.不同氮肥管理模式下,缓控释肥处理和按需施肥处理的氮环境排放量最低,比农户施肥处理分别降低了52.8%和45.4%.在等氮量投入下,有机无机配施处理比纯化肥处理减少了环境氮排放量.农户施肥处理存在着明显的氮盈余,增加了麦季氮流失的风险,按需施肥处理略微出现氮亏缺,在一定程度上减少了麦季氮流失风险.新型缓控释肥处理和按需施肥处理能在不降低产量和效益的情况下,提高氮肥利用率,减少环境排放量,是值得在太湖流域推广的经济环保氮肥管理模式.