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1.
Subsoil acidity restricts root growth and reduces crop yields in many parts of the world. More than half of the fertilizer nitrogen(N) applied in crop production is currently lost to the environment. This study aimed to investigate the effect of gypsum application on the efficiency of N fertilizer in no-till corn(Zea mays L.) production in southern Brazil. A field experiment examined the effects of surface-applied gypsum(0, 5, 10, and 15 Mg ha~(-1)) and top-dressed ammonium nitrate(NH_4NO_3)(60, 120, and 180 kg N ha~(-1)) on corn root length, N uptake, and grain yield. A greenhouse experiment was conducted using undisturbed soil columns collected from the field experiment site to evaluate NO_3-N leaching, N uptake, and root length with surface-applied gypsum(0 and 10 Mg ha~(-1)) and top-dressed NH_4NO_3(0 and 180 kg N ha~(-1)). Amelioration of subsoil acidity due to gypsum application increased corn root growth,N uptake, grain yield, and N use efficiency. Applying gypsum to the soil surface increased corn grain yield by 19%–38% and partial factor productivity of N(PFPN) by 27%–38%, depending on the N application rate. Results of the undisturbed soil column greenhouse experiment showed that improvement of N use efficiency by gypsum application was due to the higher N uptake from NO_3-N in the subsoil as a result of increased corn root length. Our results suggest that ameliorating subsoil acidity with gypsum in a no-till corn system could increase N use efficiency, improve grain yield, and reduce environmental risks due to NO_3-N leaching.  相似文献   

2.
太湖地区水稻最适宜施氮量研究   总被引:4,自引:0,他引:4  
To determine the optimal amount of nitrogen(N) fertilizer for achieving a sustainable rice production at the Taihu Lake region of China,two-year on-farm field experiments were performed at four sites using various N application rates.The results showed that 22%-30% of the applied N was recovered in crop and 7%-31% in soils at the rates of 100-350 kg N ha 1.Nitrogen losses increased with N application rates,from 44% of the applied fertilizer N at the rate of 100 kg N ha 1 to 69% of the N applied at 350 kg N ha 1.Ammonia volatilization and apparent denitrification were the main pathways of N losses.The N application rate of 300 kg N ha 1,which is commonly used by local farmers in the study region,was found to lead to a significant reduction in economic and environmental efficiency.Considering the cost for mitigating environmental pollution and the maximum net economic income,an application rate of 100-150 kg N ha 1 would be recommended.This recommended N application rate could greatly reduce N loss from 199 kg N ha 1 occurring at the N application rate of 300 kg N ha 1 to 80-110 kg N ha 1,with the rice grain yield still reaching 7 300-8 300 kg DW ha 1 in the meantime.  相似文献   

3.
不同的水稻品种产量及生理氮素利用效率的差异   总被引:6,自引:0,他引:6  
Efficient use of N in agricultural practice can increase yield, decrease production costs and reduce the risk of environmental pollution. Effects of N fertilizer application rates on grain yield and physiological N use efficiency (PE) in relation to the accumulation and redistribution of biomass and N in rice (Oryza sativa L.) cultivars were studied at two experimental farms of Nanjing Agricultural University, Nanjing, China in 2004. Three high N use efficiency (NUE) rice cultivars (Wuyunjing 7, Nanguang and 4007) and one low NUE rice cultivar (Elio) with similar growth patterns were studied under seven N rates (0, 60, 120, 180, 240, 300 and 360 kg ha-1). Grain yield increased with the N application rate and attained plateau at 180 kg N ha-1 for rice cultivars at each site. Increasing N rate decreased PE for biomass and grain yield. Grain yield and PE of Elio were about 20% and 18% lower than those of high NUE cultivars. Differences in biomass, N accumulation and N redistribution were observed at the post-heading stage among rice cultivars with differing NUEs. The less reproductive tillers of Elio resulted in less demand for C and N during grain filling, thus leading to lower PE of Elio compared with the high NUE rice cultivars.  相似文献   

4.
5.
轮作体系下冬油菜养分利用效率的区域研究   总被引:1,自引:0,他引:1  
Fertilization is essential for oilseed rape because it is sensitivity to nutrient deficiency, especially for winter oilseed rape(Brassica napus L.). To investigate regional nutrient efficiency and nutrient uptake-yield relationship of winter oilseed rape in an intensive cropping system, this study used data from 619 site-year on-farm experiments carried out in the winter oilseed rape planting area of the Yangtze River Basin, China from 2005 to 2010, with large yield in the range of 179–4 470 kg ha~(-1). Currently recommended application rates of N, P and K fertilizers increased rapeseed yield at different levels of soil indigenous nutrient supply(INS) in this region. Boundary values of plant nutrient uptake were established to analyze the nutrient uptake-yield relationship of winter oilseed rape(internal nutrient efficiency), i.e., 128 kg N ha~(-1), 24 kg P ha~(-1), and 122 kg K ha~(-1). The internal nutrient efficiency declined by 48.2%–64.1% when nutrient uptake exceeded the boundary value, resulting in excessive nutrient uptake(i.e., low yield response with high nutrient uptake), especially for K. In the intensive cropping system, agronomic efficiencies of N, P, and K were 5.9, 3.4, and3.6 kg kg~(-1), and recovery efficiencies of N, P, and K were 35.6%, 24.1%, and 36.8%, respectively. These findings showed that the fertilization rate should be optimized by considering INS, nutrient status, and nutrient efficiency of winter oilseed rape. In this study,considering the lower yield improvement to high K uptake levels and low K fertilizer efficiency, application rate of K fertilizer should be reduced since soil K deficiency has already been mitigated.  相似文献   

6.
Applying slow-release fertilizers is possible means for reducing nitrogen(N) loss in rice production. Matrix-based fertilizers represent novel slow-release fertilizers. To date, there is little consensus about the effect of combined addition of organic and inorganic matrix materials on rice production. We developed a slow-release urea fertilizer with selected organic and inorganic matrix materials. The study aimed to: i) determine the effect of the slow-release urea on rice yield, profit, and agronomic efficiency and ii) elucidate its possible mechanisms. A two-year field experiment was conducted during 2015–2016. Besides,laboratory experiments were conducted to determine the potential N loss risk. Three treatments were set up: control without N application(CK), regular urea treatment(RU, 150 kg N ha~(-1)), and slow-release urea treatment(SU, 150 kg N ha~(-1)). The results showed that rice biomass and grain yield were significantly higher in SU than in RU(P 0.05). The higher panicle density in SU was largely responsible for the greater grain yield. Net profit in SU was US$450 ha~(-1), higher than in RU. Agronomic efficiency was significantly greater in SU than in RU(P 0.05). Rice height, root area, leaf chlorophyll, leaf nitrate reductase activity, and leaf glutamine synthetase activity were larger in SU than in RU. Less N loss and greater soil N availability were partly responsible for the improvements in rice growth traits and physiological parameters in SU. Overall, the slow-release urea is a promising fertilizer for rice production.  相似文献   

7.
Diazotrophic bacteria applied as a seed inoculant can improve the grain yield of several crops including maize. The current study aimed to test the agronomic efficiency and contribution of biological nitrogen fixation(BNF) of the endophytic diazotroph Herbaspirillum seropedicae strain ZAE94 to maize under field conditions. Eighteen field assays were conducted in four different locations during consecutive years on two hybrids and two varieties of maize in a random block design with four replicates using a peat-based inoculant. The inoculant containing the ZAE94 strain was applied without nitrogen(N)fertilization or with 40 kg N ha~(-1) and was compared to the application of 40 and 80 kg N ha~(-1) without inoculation. Crop productivity and N accumulation in the grain were evaluated in addition to ~(15)N natural abundance(δ~(15)N) to evaluate BNF in the treatments without N fertilization. Fertilization at 40 kg N ha~(-1) plus bacterial inoculation produced crop yields similar to the treatment with 80 kg N ha~(-1) and increased grain N content, especially in the off-season with 40 kg N ha~(-1). The inoculation treatments showed lower δ~(15)N values than the non-inoculated treatments, which was most evident in the off-season. The BNF contributed about 30% of N accumulated in plants inoculated with ZAE94. On average, 64% of the N fertilized plots showed an increase of the parameters evaluated in the inoculated treatments, compared with the control. Inoculation also increased root length, root volume, and leaf area, and these parameters were positively correlated with plant weight using a hydroponic assay. This study revealed that the application of H. seropedicae inoculant increased the amount of N in plants owing to BNF, and there is a better chance of yield response to inoculation under low N fertilizer application in the off-season.  相似文献   

8.
Organic agricultural systems rely on organic amendments to achieve crop fertility requirements, and weed control must be achieved without synthetic herbicides. Our objective was to determine the crop yield and soil quality as affected by a transition from grass to dryland organic agriculture in the Central Great Plains of North America. This study evaluated three beef feedlot compost(BFC)treatments in 2010–2015 following biennial application rates: 0(control), 22.9, and 108.7 t ha~(-1) on two dryland organic cropping systems: a wheat(Triticum aestivum)-fallow(WF) rotation harvested for grain and a triticale(Triticosecale)/pea(Pisum sativum)-fallow(T/P-F) rotation harvested for forage. The triticale + pea biomass responded positively to the 108.7-t ha~(-1) BFC treatment,but not the 22.9-t ha~(-1) BFC treatment. The wheat biomass was not affected by BFC addition, but biomass N content increased.Beef feedlot compost input did not increase wheat grain yields, but had a positive effect on wheat grain Zn content. Soil total C and N contents increased with the rate of 108.7 t ha~(-1) BFC after three applications, but not with 22.9 t ha~(-1) BFC. Soil enzyme activities associated with N and C cycling responded positively to the 108.7-t ha~(-1) BFC treatment. Saturated salts were high in the soil receiving 108.7 t ha~(-1) of BFC, but did not affect crop yields. These results showed that BFC was effective in enhancing forage yields, wheat grain quality, and soil C and N, as well as specific microbial enzymes important for nutrient cycling. However, the large rates of BFC necessary to elicit these positive responses did not increase grain yields, and resulted in an excessive buildup of soil P.  相似文献   

9.
Pot experiments were carried out to study the effect of incorporation of wheat straw and/ or urea into soil on biomass nitrogen and mineral nitrogen and its relation to the growth and yield of rice.The combined appliation of wheat straw and urea increased much more biomass nitrogen in soil than the application of wheat straw or urea alone and consequently increased the immobilization of urea nitrogen added and reduced the loss of urea nitrogen.An adequate nitrogen-supplying process to rice plant could be obtained if C/ N ratio of the material added was about 20.The three yield components of rice were affected significantly by the status of nitrogen supplying.More than 30mg N/ kg soil of mineral nitrogen at effective tillering stage,panicle initiation stage and filling stage should be maintained in order to get high rice yield,though the criteria varied with the different experimental conditions.  相似文献   

10.
提高高产玉米氮素利用效率的根层氮素管理技术   总被引:5,自引:0,他引:5  
Many recently developed N management strategies have been extremely successful in improving N use efficiency.How-ever,attempts to further increase grain yields have had limited success.Field experiments were conducted in 2007 and 2008 at four sites to evaluate the effect of an in-season root-zone N management strategy on maize (Zea mays L.).According to the in-season root-zone N management,the optimal N rate (ONR) was determined by subtracting measured soil mineral N (NH + 4--N and NO 3--N) in the root zone from N target values.Other treatments included a control without N fertilization,70% of ONR,130% of ONR,and recommended N rate (RNR) by agronomists in China that have been shown to approach maize yield potentials.Although apparent N recovery for the ONR treatment was significantly higher than that under RNR in 2007,grain yield declined from 13.3 to 11.0 Mg ha 1 because of an underestimation of N uptake.In 2008,N target values were adjusted to match crop uptake,and N fertilization rates were reduced from 450 kg N ha-1 for RNR to 225 to 265 kg N ha-1 for ONR.High maize yields were maintained at 12.6 to 13.5 Mg ha 1,which were twice the yield from typical farmers’ practice.As a result,apparent N recovery increased from 29% to 66%,and estimated N losses decreased significantly for the ONR treatment compared to the RNR treatment.In conclusion,the in-season root-zone N management approach was able to achieve high yields,high NUE and low N losses.  相似文献   

11.
中国玉米小麦产量与氮肥利用效率同步提高的研究进展   总被引:20,自引:0,他引:20  
Achieving both high yield and high nitrogen use efficiency (NUE) simultaneously has become a major challenge with increased global demand for food, depletion of natural resources, and deterioration of environment. As the greatest consumers of N fertilizer in the world, Chinese farmers have overused N and there has been poor synchrony between crop N demand and N supply because of limited understanding of the N uptake-yield relationship. To address this problem, this study evaluated the total and dynamic N requirement for different yield ranges of two major crops (maize and wheat), and suggested improvements to N management strategies. Whole-plant N aboveground uptake requirement per grain yield (N req) initially deceased with grain yield improvement and then stagnated, and yet most farmers still believed that more fertilizer and higher grain yield were synonymous. When maize yield increased from < 7.5 to > 12.0 Mg ha-1, Nreq decreased from 19.8 to 17.0 kg Mg-1 grain. For wheat, it decreased from 27.1 kg Mg-1 grain for grain yield < 4.5 Mg ha-1 to 22.7 kg Mg-1 grain for yield > 9.0 Mg ha-1. Meanwhile, the percentage of dry matter and N accumulation in the middle-late growing season increased significantly with grain yield, which indicated that N fertilization should be concentrated in the middle-late stage to match crop demand while farmers often applied the majority of N fertilizer either before sowing or during early growth stages. We accordingly developed an integrated soil-crop system management strategy that simultaneously increases both grain yield and NUE.  相似文献   

12.
Field experiments were conducted during successive rainy seasons in 2006 in the Chau Thanh district of southern Vietnam to evaluate the effects of an inoculant plant growth promoter product called “BioGro” and N fertiliser rates on yield and N and P nutrition of rice. The results indicated that inoculation with BioGro, containing a pseudomonad, two bacilli and a soil yeast, significantly increased grain and straw yields and total N uptake in both seasons, as well as grain quality in terms of percentage N. Nitrogen fertilisation increased grain and straw yields as well as total N and P uptakes significantly in both cropping seasons. The estimated grain yield response to added N was quadratic in nature with and without added BioGro. In the first crop, BioGro out-yielded the control up to 90 kg urea N ha?1 whilst in the second season the beneficial effect of BioGro was observed up to 120 kg urea N ha?1, indicating either an interaction of the inoculant with higher yielding seasonal conditions or a cumulative effect of BioGro application. In the first season, the estimated N rate for maximum grain yield was 103 kg N ha?1 with BioGro while it was 143 kg N ha?1 without BioGro. The maximum estimated grain yields were 3.21 and 3.18 t ha?1 with and without BioGro, respectively. This information indicates that BioGro was able to save 40 kg N ha?1 with an additional rice yield of 30 kg ha?1 in the season. In the second rainy season, the estimated N rates for maximum grain yields were 94 and 97 kg N ha?1 with and without BioGro, respectively. The estimated maximum grain yields were 3.49 and 3.25 t ha?1 with and without BioGro, respectively. The two seasons’ combined results indicate that application of BioGro improved the efficiency of N use by rice significantly, saving 43 kg N ha?1 with an additional rice yield of 270 kg ha?1 in two consecutive seasons at the experimental site. The extra efficiency was shown by the fact that the same yield of rice was obtained with about 40 and 60 kg less fertiliser-N that the maximum yields with urea alone in the two successive harvests on the same plots.  相似文献   

13.
ABSTRACT

In order to formulate a nitrogen (N) management strategy under continuous full amount of straw returning (CFSR) for double cropping rice production, long-term (2013–2016) paddy field experiments were conducted in double cropping rice production area in the Jiangxi province, China. Five N fertilizer treatments under CFSR were tested, that is, (i) no N fertilizer application (CK); (ii) conventional N fertilizer application (165kg N ha?1 and 195 kg N ha?1 in early and late rice variety with the ratio of basal dressing to topdressing as 6:4, respectively) (CNF6:4); (iii) recommended N fertilizer application (135 kg ha?1 N and 165 kg ha?1 N in early and late rice variety with the ratio of basal dressing to topdressing as 4:6, 6:4, and 8:2, respectively) (RNF4:6, RNF6:4, and RNF8:2). Nitrogen fertilizer treatments under CFSR had 5.70% and 8.93% higher soil total nitrogen (TN), 1.32% and 0.80% higher available nitrogen (AN), 16.55% and 22.94% higher NH4+-N, and 13.10% and 7.93% higher NO3--N than CK treatments in early and late rice variety, respectively. There were no differences in soil TN, AN, NH4+-N, and NO3--N contents between CNF6:4 and RNF6:4 treatments, while CNF6:4 treatment showed higher or significantly higher soil N contents than RNF4:6 and RNF8:2 treatments. N fertilizer treatment under CFSR showed 88.9% and 43.20% higher grain yield and 62.15% and 42.52% higher panicle numbers than CK treatments in early and late rice variety, respectively. Compared with CNF6:4, RNF treatments did not significantly reduce grain yield and yield components in early and late rice variety, respectively, except for RNF8:2. Compared with RNF6:4 and 8:2, RNF4:6 showed higher rice grain yield, while no obvious differences in yield components were obtained among all RNF treatments. We concluded that N fertilizer under CFSR was helpful to improve soil N contents and double rice grain yield and panicle numbers. Appropriate reduction of N application (18% and 15% reduction in early and late rice variety, respectively) on the basis of adjusting ratio of basal dressing to topdressing as 4:6 and 6:4 did not significantly reduce soil TN and double rice grain yield and yield components, especially, the 40% basal N dressing and 60% N topdressing was beneficial to increase double rice grain yield under CFSR.  相似文献   

14.
The rice–wheat cropping system (RWCS), producing about 5–10 Mg ha–1 y–1 of grain, is the backbone of food‐crop production in South‐East Asia. However, this system shows signs of fatigue as indicated by declining yields, negative nitrogen (N) balances, and reduced responses to applied fertilizer at some research centers. The return of rice and wheat residues can recycle up to 20%–30% of the N absorbed by the crops. However, their wide C : N ratio can temporarily immobilize native and applied N. To overcome this immobilization, wheat‐straw application was supplemented with the incorporation of Sesbania green manure and mungbean residues, and their effects on productivity, agronomic N efficiency, and system's apparent N balances were studied. Combining the application of wheat straw with Sesbania green manure or mungbean residues increased cereal grain yield and agronomic N efficiency and improved the generally negative apparent N balances. The combined use of wheat straw and mungbean produced an additional 0.5–0.6 t ha–1 protein‐rich grain and thus appears to be the most promising residue‐management option for rice–wheat cropping systems in South Asia, provided that the transition cropping season between wheat harvest and rice transplanting is long enough.  相似文献   

15.
Abstract

Results of 240 annual N fertilizer trials in 1991–2007 in spring and winter cereals are presented. On average, spring barley and oat yields increased little beyond 120 kg N ha?1 in fertilizer. Somewhat higher figures were found for spring and winter wheat. Regression equations for yield and N uptakes in grain and straw were derived, related to N fertilizer input and the yield level in individual trials (indicator of yield expectancy). These equations accounted for 90% of the variation in yield and 80% of that in N uptake. Quadratic N responses were significant in all cases, as were interactions between N responses and yield level. They were verified with data from 27 separate trials performed in 2008–2010. The yield equations were used to calculate economically optimum N fertilizer levels with varying ratios of product price to fertilizer cost at contrasting levels of yield. The optimum N fertilizer level for barley and oats was found to increase by 8.3 kg N ha?1 per Mg increase in expected yield. The equivalent figure in wheat was 16.3 kg N ha?1. Optimum N fertilizer levels decreased by 4.1 and 6.7 kg N ha?1, for barley/oats and wheat respectively, per unit increase in the cost/price ratio. The equations for N uptake were used to calculate simple N balances between fertilizer input and removal in crop products. Large N surpluses were indicated at low levels of yield expectancy, but the surplus declined markedly with increasing yield level, despite greater N fertilizer inputs at high yield. Calculations made for national average yield levels in recent years showed N surpluses of 50–60 kg N ha?1 when only grain is removed and 25–40 kg N ha?1 when straw is removed also. Limiting N input to obtain zero balance reduces yields considerably at average levels of yield expectancy.  相似文献   

16.
Field experiments were carried out during rainy (kharif) and winter (rabi) seasons (June–April) of 2008–2010 at Indian Agricultural Research Institute (IARI), New Delhi, to study the productivity, nutrients uptake, iron (Fe) use-efficiency and economics of aerobic rice-wheat cropping system as influenced by mulching and Fe nutrition. The highest yield attributes, grain and straw yields (5.41 tonnes ha?1 and 6.56 tonnes ha?1, respectively) and nutrient uptake in rice was recorded with transplanted and puddled rice (TPR) followed by aerobic rice with Sesbania aculeata mulch. However, residual effect of aerobic rice with wheat straw mulch was more pronounced on yield attributes, grain and straw yields (4.20 and 6.70 tonnes ha?1, respectively) and nutrient uptake in succeeding wheat and remained at par with aerobic rice with Sesbania mulch. Application of iron sulfate (FeSO4) at 50 kg ha?1 + 2 foliar sprays of 2% FeSO4 was found to be the best in terms of all the yield attributes, grain and straw yield (5.09 and 6.17 tonnes ha?1, respectively) and nutrient uptake and remained at par with 3 foliar sprays of 2% FeSO4. Although residual effect of iron application failed to increase the yield attributes, yield and nutrient uptake nitrogen, phosphorus and potassium (N, P, K) except Fe. The highest system productivity, nutrient uptake, gross returns, net returns, B: C ratio and lowest cost of cultivation were recorded with aerobic rice with wheat straw and Sesbania aculeata mulch. Application of FeSO4 at 50 kg ha?1 + two foliar sprays of 2% FeSO4 was found better in respect of system productivity, nutrient uptake, gross returns, net returns, B:C ratio and cost of cultivation in aerobic rice-wheat cropping system. The Fe use efficiency values viz. partial factor productivity (kg grain kg?1 Fe), agronomic efficiency (kg grain increased kg?1 Fe applied), agrophysiological efficiency (kg grain kg?1 Fe uptake), physiological efficiency (kg biomass kg?1 Fe uptake), apparent recovery (%) utilization efficiency and harvest index (%) of applied Fe were significantly affected due to methods of rice production and various Fe nutrition treatments in aerobic rice and aerobic rice-wheat cropping system.  相似文献   

17.
Information on the combined use of organic and inorganic fertilizers on wheat (Triticum aestivum L.) productivity is lacking under moisture stress conditions of Northwest Pakistan. The present experiment was designed to ascertain the combined effect of organic and inorganic fertilizer management on rainfed wheat. Four levels of farm yard manure, FYM, (0, 10, 20, and 30 Mg FYM ha?1) and nitrogen (0, 30, 60, 90, and 120 kg N ha?1) were used. The experiment was conducted at the Agriculture Research Farm of NWFP Agricultural University Peshawar, Pakistan during crop season of 2003–04. The experiment was laid out in randomized complete block design with four replications. Plant height, productive tillers m?2, grains spike?1, grain yield, straw yield, and harvest index were significantly higher in plots which received 30 Mg FYM ha?1. In the case of nitrogen (N) no distinctive differences between the effect of 90 and 120 kg ha?1 was observed for most of the parameters. Nitrogen application at 90 kg ha?1 had significantly higher; plant height, grains spike?1, grain yield, straw yield, and harvest index as compared with the lower levels, i.e., 0, 30, and 60 kg N ha?1 but were at par with 120 N kg ha?1. Significantly higher numbers of productive tillers m?2, grains spike?1, grain yield, straw yield and harvest index were recorded with application of 30 Mg FYM ha?1 + 90 kg N ha?1. The present study suggested that application of 30 Mg FYM ha?1 + 90 kg N ha?1 are promising levels for higher production of wheat under moisture stress conditions. Further research work is needed to ascertain the effect of N above 90 kg ha?1 under different moisture regimes.  相似文献   

18.
Nitrogen and weeds are two important factors that influence the productivity of rainfed upland rice (Oryza sativa L.) in tropical Asia. A low recovery of applied fertilizer N in rainfed uplands is generally associated with high nitrate leaching losses and weed interferences. Field experiments were conducted during the wet seasons of 2002 and 2003 at the research farm of Central Rainfed Upland Rice Research Station, Hazaribag, Jharkhand, India, to determine the response of upland rice to nitrogen applied at 60 kg N ha–1 as different forms of urea (single pre‐plant application of controlled‐release urea, single pre‐plant application of urea supergranules, and split application of prilled urea with or without basal N) against no N application under three weed‐control regimes (unweeded, pre‐emergence application of butachlor at 1.5 kg a.i. ha–1 supplemented with one single hand weeding or two hand weedings). The response of rice to applied N varied greatly among the three weed‐control regimes. Across the different N treatments, the application of 60 kg N ha–1 resulted in a grain‐yield increase above the unfertilized control of only 0.24 Mg ha–1 in unweeded treatments, whereas yields increased by 1.07 Mg ha–1 when butachlor application was supplemented with a single hand weeding and by 1.28 Mg ha–1 with two hand weedings. Among the weed‐control measures, hand weeding twice produced highest grain yield in both years. The comparison of different forms of urea showed that a single pre‐plant application of controlled‐release urea resulted in average grain yields of 1.57 and 1.87 Mg ha–1 compared to 1.32 and 1.30 Mg ha–1 in the case of the recommended practice of split‐applied prilled urea in the years 2002 and 2003, respectively. The highest agronomic N use efficiency of 15–20 kg grain per kg N applied and the highest apparent N recovery of 39%–45% were attained with controlled‐release urea, suggesting that this N form is particularly beneficial for upland‐rice cultivation under variable rainfall conditions, provided weeds are controlled.  相似文献   

19.
China has the world''s highest nitrogen (N) application rate, and the lowest N use efficiency (NUE). With the crop yield increasing, serious N pollution is also caused. An in-situ field experiment (2011-2015) was conducted to examine the effects of three N levels, 0 (i.e., no fertilizer N addition to soil), 120, and 180 kg N ha-1, using integrated rice management (IRM). We investigated rice yield, aboveground N uptake, and soil surface N budget in a hilly region of Southwest China. Compared to traditional rice management (TRM), IRM integrated raised beds, plastic mulch, furrow irrigation, and triangular transplanting, which significantly improved rice grain yield, straw biomass, aboveground N uptake, and NUE. Integrated rice management significantly improved 15N recovery efficiency (by 10%) and significantly reduced the ratio of potential 15N loss (by 8%-12%). Among all treatments, the 120 kg N ha-1 level under IRM achieved the highest 15N recovery efficiency (32%) and 15N residual efficiency (29%), with the lowest 15N loss ratio (39%). After rice harvest, the residual N fertilizer did not achieve a full replenishment of soil N consumption, as the replenishing effect was insufficient (ranging from -31 to -49 kg N ha-1). Furthermore, soil surface N budget showed a surplus (69-146 kg N ha-1) under all treatments, and the N surplus was lower under IRM than TRM. These results indicate IRM as a reliable and stable method for high rice yield and high NUE, while exerting a minor risk of N loss. In the hilly area of Southwest China, the optimized N fertilizer application rate under IRM was found to be 100-150 kg N ha-1.  相似文献   

20.
ABSTRACT

Nutrient uptake and grain and straw yield of Egyptian winter wheat (Triticum aestivum L. Merr.) were evaluated for two site-years after the seed inoculation with two biofertilizer products, Phosphorien, containing the phosphorus (P)-solubilizing bacteria Bacillus megatherium, and Nitrobien, containing a combination of nitrogen (N)-fixing bacteria Azotobacter chroococcum and Azospirillum liposerum. Ammonium nitrate and polymer-coated urea fertilizers were applied to plots alone and together with the biofertilizers at rates of either 83 kg N ha?1 or 186 kg N ha?1 for comparison. The highest grain yield (5.76–6.74 Mg ha?1) and straw yield (11.49–13.32 Mg ha?1) occurred at the highest fertilizer rates with N fertilizer. There was a slight additional increase in grain and straw yields when a biofertilizer was applied along with N fertilizer. A slightly higher grain and straw yield was measured with the polymer-coated urea treatment than with the ammonium nitrate treatment. The biofertilizer materials were not as effective as N fertilizers in producing grain (4.02–4.09 Mg ha?1) or straw (7.71–8.11 Mg ha?1) for either year, although the Nitrobien + Phosphorien combination increased these parameters over the N-fertilizer control. The effect of the Nitrobien biofertilizer in increasing grain yields was equivalent to a urea application rate of about 13 kg N ha?1. Biofertilizer inoculations increased iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) concentrations in wheat tissue (at boot stage), but these higher levels did not influence grain or straw yield.  相似文献   

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