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1.
Coupling winter small grain cover crops (CC) with manure (M) application may increase retention of manure nitrogen (N) in corn (Zea mays L.), -soybean [Glycine max (L.) Merr], cropping systems. The objective of this research was to quantify soil N changes after application of liquid swine M (Sus scrofa L.) at target N rates of 112, 224, and 336 kg N ha−1 with and without a CC. A winter rye (Secale cereale L.)-oat (Avena sativa L.) CC was established prior to fall M injection. Surface soil (0–20 cm) inorganic N concentrations were quantified every week for up to 6 weeks after M application in 2005 and 2006. Soil profile (0–120 cm in 5, 20-cm depth increments) inorganic N, total N, total organic carbon and bulk density were quantified for each depth increment in the fall before M application and before the CC was killed the following spring. Surface soil inorganic N on the day of application averaged 318 \textmg  \textN  \textkg - 1\textsoil 318\,{\text{mg}}\;{\text{N}}\;{\text{kg}}^{ - 1}{_{\text{soil}}} in 2005 and 186 \textmg  \textN  \textkg - 1\textsoil 186\,{\text{mg}}\;{\text{N}}\;{\text{kg}}^{ - 1}{_{\text{soil}} } in 2006 and stabilized at 150 \textmg  \textN  \textkg - 1\textsoil 150\,{\text{mg}}\;{\text{N}}\;{\text{kg}}^{ - 1}{_{\text{soil}}} in both years by mid-November. Surface soil NO3-N concentrations in the M band were more than 30 times higher in the fall of 2005 than in 2006. The CC reduced surface soil NO3-N concentrations after manure application by 32% and 67% in mid- November 2005 and 2006, respectively. Manure applied at 224 kg N ha−1 without a CC had significantly more soil profile inorganic-N (480 kg N ha−1) in the spring after M application than manured soils with a CC for the 112 (298 kg N ha−1) and 224 (281 kg N ha−1) N rates, and equivalent inorganic N to the 336 (433 kg N ha−1) N rate. These results quantify the potential for cover crops to enhance manure N retention and reduce N leaching potential in farming systems utilizing manure.  相似文献   

2.
A computer model is described that simulates leaching, organic matter turnover and nitrogen uptake by a winter wheat crop. The model is assessed against a data set from the Netherlands where winter wheat was grown in two seasons (1982–3 and 1983–4) on three different soils in two different parts of the country. The model satisfactorily simulated the growth, N uptake and production of grain. It also simulated the dynamics of indigenous soil N well but it did not always account for the fate of applied fertilizer N. Some possible reasons for this and ways of improving the model are discussed.  相似文献   

3.
In this study, we measured nitrous oxide (N2O) fluxes from plots of fall-planted hairy vetch (HV, Vicia villosa) and spring-planted broadleaf vetch (BLV, Vicia narbonensis) grown as nitrogen (N) sources for following summer forage crabgrass (Digitaria sanguinalis). Comparisons also included 60 kg ha?1 inorganic N fertilizer for crabgrass at planting (60-N) and a control without N fertilizer. Each treatment had six replicated plots across the slope. Fluxes were measured with closed chamber systems during the period between spring growth of cover crops and first-cut of crabgrass in mid-July. HV had strong stand and aboveground biomass had 185?±?50 kg N ha?1 (mean?±?standard error, n?=?6) at termination. However, BLV did not establish well and aboveground biomass had only 35?±?15 kg N ha?1. Ratio vegetation index of crabgrass measured as proxy of biomass growth was highest in HV treatment. However, total aboveground biomass of crabgrass was statistically similar to 60-N plots. Fluxes of N2O were low prior to termination of cover crops but were as high as 8.2 kg N2O ha?1 day?1 from HV plots after termination. The fluxes were enhanced by large rainfall events recorded after biomass incorporation. Rainfall enhanced N2O fluxes were also observed in other treatments, but their magnitudes were much smaller. The high N2O fluxes from HV plots contributed to emissions of 30.3?±?12.4 kg N2O ha?1 within 30 days of biomass incorporation. Emissions were only 2.0?±?0.7, 3.4?±?1.3 and 1.0?±?0.4 kg N2O ha?1 from BLV, 60-N and control plots, respectively.  相似文献   

4.
5.
The nitrogen (N) use efficiency of field vegetable production systems needs to be increased in order to, reduce the detrimental effects of N losses on other ecosystems, save on production costs, and meet the limits set by the German government concerning N balance surpluses. Winter catch crops (CCs) have been shown to be a useful tool for reducing N losses in many agricultural production systems. This study was designed to test the effects of different CCs: rye (Secale cereale L.), fodder radish (Raphanus sativus L. var. oleiformis Pers.), bunch onion (Allium cepa L.), and sudangrass (Sorghum sudanense Stapf), planted at different sowing dates (early, late), on the N balance of 2-year vegetable crop rotation systems. The crop rotations started with a cauliflower (Brassica oleracea L. var. botrytis L.) crop, which was fertilized with N in a conventional manner. The experiments took place at three different sites in Germany. Results revealed that the average N balance surplus, when taking into consideration, fertilization, soil mineral N, and aboveground plant biomass N, was 217 kg N ha−1 in the control treatments without a CC. This high value was mainly a consequence of large quantities of crop N and soil mineral N remaining after the harvest of the cauliflower. In spite of these high N surpluses, the application of CC only reduced the N balance surplus, on average across all sites and experiments, by 13 kg N ha−1, when compared to the control treatments. The type of CC and the sowing date had only minor effects on the N balance. The findings of this study suggest that for many sites the application of CCs does not solve the problem of high N balance surpluses in intensive field vegetable production systems.  相似文献   

6.
Nutrient Cycling in Agroecosystems - Legume cover crops can play a valuable role in maintaining and increasing soil quality and nitrogen availability, but are infrequently grown in the Upper...  相似文献   

7.
Nitrogen (N) management is a key issue in livestock-free organic grain systems. Relay intercropping with a legume cover crop can be a useful technique for improving N availability when two cash crops are grown successively. We evaluated the benefits of four relay intercropped legumes (Medicago lupulina, Medicago sativa, Trifolium pratense and Trifolium repens) on N dynamics and their contribution to the associated and subsequent cash crops in six fields of organic farms located in South-East France. None of the relay intercropped legumes affected the N uptake of the associated winter wheat but all significantly increased the N uptake of the succeeding spring crop, either maize or spring wheat. The improvement of the N nutrition of the subsequent maize crop induced a 30 % increase in grain yield. All relay intercropped legumes enriched the soil–plant system in N through symbiotic fixation. From 71 to 96 % of the N contained in the shoots of the legumes in late autumn was derived from the atmosphere (Ndfa) and varied between 38 and 67 kg Ndfa ha?1. Even if the cover crop is expected to limit N leaching during wintertime, the presence of relay intercropped legumes had no significant effect on N leaching during winter compared to the control.  相似文献   

8.
Nutrient Cycling in Agroecosystems - In order to test the efficacy of conservation tillage and optimized fertilization on reducing N and P runoff losses, a 4-year (2007–2011) runoff plot...  相似文献   

9.
Smallholder land productivity in drylands can be increased by optimizing locally available resources, through nutrient enhancement and water conservation. In this study, we investigated the effect of tillage system, organic resource and chemical nitrogen fertilizer application on maize productivity in a sandy soil in eastern Kenya over four seasons. The objectives were to (1) determine effects of different tillage-organic resource combinations on soil structure and crop yield, (2) determine optimum organic–inorganic nutrient combinations for arid and semi-arid environments in Kenya and, (3) assess partial nutrient budgets of different soil, water and nutrient management practices using nutrient inflows and outflows. This experiment, initiated in the short rainy season of 2005, was a split plot design with 7 treatments involving combinations of tillage (tied-ridges, conventional tillage and no-till) and organic resource (1 t ha−1 manure + 1 t ha−1 crop residue and; 2 t ha−1 of manure (no crop residue) in the main plots. Chemical nitrogen fertilizer at 0 and 60 kg N ha−1 was used in sub-plots. Although average yield in no-till was by 30–65% lower than in conventional and tied-ridges during the initial two seasons, it achieved 7–40% higher yields than these tillage systems by season four. Combined application of 1 t ha−1 of crop residue and 1 t ha−1 of manure increased maize yield over sole application of manure at 2 t ha−1 by between 17 and 51% depending on the tillage system, for treatments without inorganic N fertilizer. Cumulative nutrients in harvested maize in the four seasons ranged from 77 to 196 kg N ha−1, 12 to 27 kg P ha−1 and 102 to 191 kg K ha−1, representing 23 and 62% of applied N in treatments with and without mineral fertilizer N respectively, 10% of applied P and 35% of applied K. Chemical nitrogen fertilizer application increased maize yields by 17–94%; the increases were significant in the first 3 seasons (P < 0.05). Tillage had significant effect on soil macro- (>2 mm) and micro-aggregates fractions (<250 μm >53 μm: P < 0.05), with aggregation indices following the order no-till > tied-ridges > conventional tillage. Also, combining crop residue and manure increased large macro-aggregates by 1.4–4.0 g 100 g−1 soil above manure only treatments. We conclude that even with modest organic resource application, and depending on the number of seasons of use, conservation tillage systems such as tied-ridges and no-till can be effective in improving crop yield, nutrient uptake and soil structure and that farmers are better off applying 1 t ha−1 each of crop residue and manure rather than sole manure.  相似文献   

10.
The processes affecting the response of crops to nitrogen fertilizers are reviewed, with special emphasis on quantitative relationships that enable the development of deterministic models. Total dry matter production is described in terms of length of the growing period and average growth rate, and the effect of nitrogen status of the vegetation on both is discussed. Attention is paid to nitrogen influence on stomatal response and crop water use. It is shown that the effect of differential nitrogen nutrition can in some cases be described in terms of light interception, but not always. It is concluded that the present insight in the relevant processes is insufficient to use deterministic models directly for application in fertilizer practices at the farm level, but that further development of such models is an important aid in structuring thinking about the system.  相似文献   

11.
A model that simulates changes in mineral N in the soil and N uptake by crops has been adapted to require as little detailed information as possible so that it is useful as an aid to management. The adapted model, which was developed in the UK, was tested against data from six experiments on winter wheat in the Netherlands. It proved reasonably successful in simulating the amounts of mineral N found in the soil in early spring and the changes that resulted from applying small amounts of fertilizer N in February. It was much less successful in simulating the effects of later, larger applications of N, mainly because the mineral N measured in the soil did not seem to respond to these applications. The uptake of N by the crops and their production of dry matter were simulated very well in some cases and rather less so in others.  相似文献   

12.
Nutrient Cycling in Agroecosystems - Winter oilseed crops camelina [Camelina sativa (L.) Crantz] and field pennycress (Thlaspi arvense L.) are potential candidates for diversifying the...  相似文献   

13.
The development of sustainable agricultural systems for the tropics requires among other technologies, alternatives for nitrogen fertilizers which are often limited in availability for financial reasons and also represent a major source of groundwater and air pollution. There are many new alternatives for the development of agricultural systems which make use of biological processes in soil. Biological nitrogen fixation (BNF), that is, the biological conversion of atmospheric dinitrogen into mineral N, is the most important alternative among them. Examples are given of the impact of various technologies used in Brazil. Soybean, introduced into the country 30 years ago, is now the second most important export crop, reaching 24 million tons annually with no N fertilizer application. Consequently, Brazil today is the country in the world which uses the lowest amounts of nitrogen fertilizers in relation to phosphate. Alternatives for crop rotations and pastures are also discussed. Possibilities of expanding BNF to cereals and other non-legume crops are gaining new credibility due to the identification of endophytic associations with diazotropic bacteria. The definite proof of substantial BNF in sugar cane with N balance and15N methods in certain genotypes selected under low N fertilizer applications opens up new alternatives for sustainable agriculture and will be the key to viable bio-fuel programmes.  相似文献   

14.
The Nitrate Directive of the European Union (EU) forces agriculture to reduce nitrate emission. The current study addressed nitrate emission and nitrate-N concentrations in leachate from cropping systems with and without the cultivation of catch crops (winter rye: Secale cereale L. and forage rape: Brassica napus ssp. oleifera (Metzg.) Sinksk). For this purpose, ceramic suction cups were used, installed at 80 cm below the soil surface. Soil water samples were extracted at intervals of ca 14 days over the course of three leaching seasons (September – February) in 1992–1995 on sandy soil in a crop rotation comprising potato (Solanum tuberosum L.), spring wheat (Triticum aestivum L.), sugar beet (Beta vulgaris L.) and oats (Avena sativa L.). Nitrate-N concentration was determined in the soil water samples. In a selection of samples several cations and anions were determined in order to analyze which cations primarily leach in combination with nitrate. The water flux at 80 cm depth was calculated with the SWAP model. Nitrate-N loss per interval was obtained by multiplying the measured nitrate-N concentration and the calculated flux. Accumulation over the season yielded the total nitrate-N leaching and the seasonal flux-weighted nitrate-N concentration in leachate. Among the cases studied, the total leaching of nitrate-N ranged between 30 and 140 kg ha–1. Over the leaching season, the flux-weighted nitrate-N concentration ranged between 5 and 25 mg L–1. Without catch crop cultivation, that concentration exceeded the EU nitrate-N standard (11.3 mg L–1) in all cases. Averaged for the current rotation, cultivation of catch crops would result in average nitrate-N concentrations in leachate near or below the EU nitrate standard. Nitrate-N concentrations correlated with calcium concentration and to a lesser extent with magnesium and potassium, indicating that these three ion species primarily leach in combination with nitrate. It is concluded that systematic inclusion of catch crops helps to decrease the nitrate-N concentration in leachate to values near or below the EU standard in arable rotations on sandy soils.  相似文献   

15.
Irrigation water and nitrogen (N) are the limiting factors for crop production in arid and semi-arid areas. However, excess irrigation and N application rate is a source of groundwater contamination. Partial root drying irrigation (PRD) is the water-saving technique and would perform as a controlling measure of groundwater N contamination as it reduces irrigation amount. Sugar beet is an industrial crop that is widely grown in arid and semi-arid area where N and water are highly required for high sugar beet yield production. The objectives of this study were to evaluate the interaction effect of ordinary furrow irrigation (OFI), and PRD irrigation as variable alternate furrow irrigation (VAFI) and fixed alternate furrow irrigation (FAFI) with different N application rates (0, 80, 160, and 240 kg ha?1) on sugar beet root and sugar yield, yield quality, drainage water, N leaching, N uptake, and N efficiency indices. Results indicated that the alternate furrow irrigation (AFI) used 24% less irrigation water compared with the OFI in the study region, whereas its sugar yield was reduced just by 9%. However, it resulted in higher water productivity by 12 and 17% for root and sugar yields, respectively. In different N application rates nitrate leaching reduced by 46 and 52% in the VAFI and FAFI irrigation treatments compared with the OFI, respectively. Physiologic nitrogen efficiency enhanced in VAFI with 160 kg N ha?1 that implied higher production of uptake N in plants. Therefore, considering the nitrogen use economics and environmental impacts, the VAFI and 160 kg N ha?1 were preferred to the other irrigation treatments and N application rates in the study region. Higher nitrogen saving occurred because of less leaching and higher soil residual in the AFI treatment compared with the OFI. Furthermore, leaf level stress sensitivity index indicated that VAFI increased the sugar beet resistance to water stress. Overall, in order to avoid N losses in sugar beet production, the amount of N fertilizer should be reduced in proportion to the amount of soil water available under VAFI water-saving irrigation.  相似文献   

16.
Field experiments with 5 levels of Nitrogen (0 to 200 kg/ha) and 4 crops—chicory(Chocorium intybus), fodder beet(Beta vulgaris), Jerusalem artichoke(Helianthus tuberosus) and grain sorghum(Sorghum bicolor) that have shown promise for alcohol production were conducted at 2 locations in California. Nitrogen uptake patterns, were evaluated and N cost for producing plant storage parts and fermentable carbohydrate were calculated. The crops were compared on these criteria. The yields of vegetative and storage organs during the crop growth are reported and their rate of change with growing time were determined. Yields of vegetative parts and total biomass of Jerusalem artichoke (JA) and grain sorgum (GS) were higher than to that of chicory (CH) and fodderbeet (FB). However, due to their lower harvest index, JA and GS produced lower yields of fermentable carbohydrate and at a much higher N cost than CH and FB. Fodder beet had the highest N uptake and the response to applied N was linear. Chicory and fodder beet which had lower N uptake rates continued N uptake from soil for a longer period than either grain sorghum or Jerusalem artichoke. The N uptake of the four crops were in the decreasing order of fodder beet, grain sorghum, Jerusalem artichoke, and chicory. With N application, N concentrations of vegetative as well as storage part increased in all the crops, however, a greater proportion of applied N went into vegetative parts. At both locations, CH had the lowest N cost per unit fermentable carbohydrate produced.  相似文献   

17.
Simulating water and nitrogen behaviour in soils cropped with winter wheat   总被引:1,自引:0,他引:1  
The SWATNIT model [26], predicting water and nitrogen transport in cropped soils, was evaluated on experimental data of winter wheat for different N treatments. The experiments were monitored at three different locations on different soil types in the Netherlands. Crop growth was simulated using the SUCROS model [11] which was integrated in the SWATNIT model. Both water and nitrogen stress were incorporated. Except for the soil hydraulic properties, all model parameters were taken from literature. The model performance was evaluated on its capability to predict soil moisture profiles, nitrate and ammonia profiles, the time course of simulated total dry matter production and LAI; and crop N-uptake. Results for the simulations of the soil moisture profile indicate that the soil hydraulic properties did not reflect the actual physical behaviour of the soil with respect to soil moisture. Good agreement is found between the measured and simulated nitrate and ammonia profiles. The simulation of the nitrate content of the top layer at Bouwing was improved by increasing the NH 4 + -N-distribution coefficient thereby improving the simulation of the NH 4 + -N-content in this layer. Deviations between simulated and measured nitrate concentrations also occurred in the bottom layers (60–100 cm) of the soil profile. The phreatic ground water might influence the nitrate concentrations in the bottom layers. Concerning crop growth modelling, improvements are needed with respect to the partitioning of total dry matter production over the different plant organs in function of the stress, the calculation of the nitrogen stress and the total nitrogen uptake of the crop through a better estimate of the N-demand of the different plant organs.  相似文献   

18.
Proper management of manure nitrogen (N) requires the ability to match the rate and extent of manure N availability with crop needs. This includes recognizing the potential importance of N contributions from residual manure N that accumulates with repeated applications. Nitrogen availability relative to barley needs was assessed in plots with 13–16 years continuous histories of contrasting manure-based (solid-bedded beef) and fertilizer-based soil treatments in the Maine Potato Ecosystem Project. Soil and barley samples were collected every 7–14 days during 2003–2005, and once in 2006. Barley dry matter and N content were equivalent between the two systems. In the manure-based system, temporal patterns of N availability were more synchronous with early season crop needs than in the fertilizer-based system, but continued mineralization after harvest was also observed. In 2004–2006, samples were collected from subplots where manure/fertilizer was withheld to estimate the proportion of available N originating from current versus previous manure applications. Apparent N recovery of current years’ applications of manure organic N was 8–11% and less than predicted by a standard decay series model for beef manure (25%), highlighting the need to adjust manure N credits for crops with shorter growing seasons and lower N uptake capacities than corn. The relative contribution of residual manure N to total manure N uptake was greater than predicted from the decay series model, providing support for a residual N effect from repeated manure applications that is not accounted for in standard manure recommendations.  相似文献   

19.
Controlled study was conducted with five farm-based organic residues to predict the expected nitrogen availability with time, based on N concentration and C/N ratio of the residues under two moisture availability situations. Two kg of red loamy sand soil representing Alfisol and related soil was incubated with the residues to supply 40 kg N ha–1 at 28 ± 1°C at field capacity (FC) and 50% FC moisture conditions. Results obtained indicated that N content in soil released from residues increased with the time allowed for decomposition reactions at both FC and 50% FC moisture regimes. Relatively higher amount of N release was observed in case of legume residues like mungbean (Vigna radiata),L. leucocephala and perennial pigeonpea (Cajanus cajan), although the rate of N release was more with low N concentration residues. Sorghum stover with C/N ratio of 72.1 resulted in immobilization of N upto 90 days. Nitrogen release was higher at FC than 50% FC. The critical N concentrations of the residues at which N neither released nor immobilized decreased with the length of incubation. At 50% FC the critical concentrations were higher than at FC.  相似文献   

20.
The common relation yield / nitrogen dose can be broken into two relations: nitrogen uptake / nitrogen dose and yield / nitrogen uptake. Such procedure narrows the original variation and separates it in two different and easier to recognise categories, external and internal. The results of permanent field experiments conducted in Poland with all the most important arable crops has been re-examined according to this idea. The model for fertilizer recommendations in respect to nitrogen was proposed.  相似文献   

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