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1.
《European Journal of Agronomy》2006,24(1):35-44
Data from a field experiment (1995–2000) conducted on a fertile sandy loess in the Hercynian dry region of central Germany were used to determine the energy efficiency of winter oilseed rape (Brassica napus L.) as affected by previous crop and nitrogen (N) fertilization. Depending on the previous crop, winter oilseed rate was cultivated in two different crop rotations: (1) winter barley (Hordeum vulgare L.)–winter oilseed rape–winter wheat (Triticum aestivum L.), and (2) pea (Pisum sativum L.)–winter oilseed rape–winter wheat. Fertilizer was applied to winter oilseed rape as either calcium ammonium nitrate (CAN) or cattle manure slurry. The N rates applied to winter oilseed rape corresponded to 0, 80, 160 and 240 kg N ha−1 a−1.Results revealed that different N management strategies influenced the energy balance of winter oilseed rape. Averaged across years, the input of energy to winter oilseed rape was highly variable ranging from 7.42 to 16.1 GJ ha−1. Lowest energy input occurred when unfertilized winter oilseed rape followed winter barley, while the highest value was obtained when winter oilseed rape received 240 kg N ha−1 organic fertilization and followed winter barley. The lowest energy output (174 GJ ha−1), energy from seed and straw of winter oilseed rape, was observed when winter oilseed rape receiving 80 kg N ha−1 as organic fertilizer followed winter barley. The energy output increased to 262 GJ ha−1 for winter oilseed rape receiving 240 kg N ha−1 as mineral fertilizer followed pea. The energy efficiency was determined using the parameters energy gain (net energy output), energy intensity (energy input per unit grain equivalent GE; term GE is used to express the contribution that crops make to the nutrition of monogastric beings), and output/input ratio. The most favourable N rate for maximizing energy gain (250 GJ ha−1) was 240 kg N ha−1, while that needed for minimum energy intensity (91.3 MJ GE−1) was 80 kg N ha−1 and for maximum output/input ratio (29.8) was 0 kg N ha−1. 相似文献
2.
The sustainability of growing a maize—winter wheat double crop rotation in the North China Plain (NCP) has been questioned due to its high nitrogen (N) fertiliser use and low N use efficiency. This paper presents field data and evaluation and application of the soil–vegetation–atmosphere transfer model Daisy for estimating crop production and nitrate leaching from silty loam fields in the NCP. The main objectives were to: i) calibrate and validate Daisy for the NCP pedo-climate and field management conditions, and ii) use the calibrated model and the field data in a multi-response analyses to optimise the N fertiliser rate for maize and winter wheat under different field managements including straw incorporation.The model sensitivity analysis indicated that a few measurable crop parameters impact the simulated yield, while most of the studied topsoil parameters affect the simulated nitrate leaching. The model evaluation was overall satisfactory, with root mean squared residuals (RMSR) for simulated aboveground biomass and nitrogen content at harvest, monthly evapotranspiration, annual drainage and nitrate leaching out of the root zone of, respectively, 0.9 Mg ha−1, 20 kg N ha−1, 30 mm, 10 mm and 10 kg N ha−1 for the calibration, and 1.2 Mg ha−1, 26 kg N ha−1, 38 mm, 14 mm and 17 kg N ha−1 for the validation. The values of mean absolute deviation, model efficiency and determination coefficient were also overall satisfactory, except for soil water dynamics, where the model was often found erratic. Re-validation run showed that the calibrated Daisy model was able to simulate long-term dynamics of crop grain yield and topsoil carbon content in a silty loam field in the NCP well, with respective RMSR of 1.7 and 1.6 Mg ha−1. The analyses of the model and the field results showed that quadratic, Mitscherlich and linear-plateau statistical models may estimate different economic optimal N rates, underlining the importance of model choice for response analyses to avoid excess use of N fertiliser. The analyses further showed that an annual fertiliser rate of about 300 kg N ha−1 (100 for maize and 200 for wheat) for the double crop rotation with straw incorporation is the most optimal in balancing crop production and nitrate leaching under the studied conditions, given the soil replenishment with N from straw mineralisation, atmospheric deposition and residual fertiliser.This work provides a sound reference for determining N fertiliser rates that are agro-environmentally optimal for similar and other cropping systems and regions in China and extends the application of the Daisy model to the analyses of complex agro-ecosystems and management practices under semi-arid climate. 相似文献
3.
When grassland is ploughed and reseeded this results in an increased mineralization of organically bound nitrogen (N) in the soil. Greater amounts of nitrate in autumn are at risk of being leached during the winter half of the year. In two field experiments, nitrate leaching was measured over 2 years after reseeding of a 9‐year‐old grassland field in spring on a sandy soil in northwest Germany. During the experiments, major management factors that can influence the intensity of mineralization were varied: Type of fertilizer, mineral N fertilizer or organic manure, and the level of fertilization, 0, 160 or 320 kg N ha−1 a−1, before renewal of the grassland, and level of fertilization, 0, 160 or 320 kg N ha−1 a−1 in mineral form, after renewal of the grassland. The type of fertilization as well as the level of N fertilization before ploughing had no significant effect on the soil mineral nitrogen content (SMN) in autumn and N leaching in the year following the grassland renewal. N fertilizer level after sward renovation had a significant effect on the nitrate leaching losses in the two following years. Fertilization at a rate of 320 kg N ha−1 resulted in leaching losses of 7 and 61 kg N ha−1 in the first and second subsequent years, respectively. At fertilizer rates of 0 and 160 kg N ha−1 leaching losses were lower than 5 kg N ha−1. It is concluded that for mown grassland no restriction of the N fertilization before the renovation of the sward is necessary to reduce the nitrate leaching risk as long as the amount of N fertilized does not exceed the N‐uptake by the crop. Similarly, the N fertilization after the sward renewal does not bear a particular leaching risk. 相似文献
4.
High rates of nitrogen (N) fertilizer may increase N leaching with drainage, especially when there is no further crop response. It is often discussed whether leaching is affected only at levels that no longer give an economic return, or whether reducing fertilization below the economic optimum could reduce leaching further. To study nitrate leaching with different fertilizer N rates (0–135 kg N ha−1) and grain yield responses, field experiments in spring oats were conducted in 2007, 2008 and 2009 on loamy sand in south-west Sweden. Nitrate leaching was determined from nitrate concentrations in soil water sampled with ceramic suction cups and measured discharge at a nearby measuring station. The results showed that nitrate leaching per kg grain produced had its minimum around the economic optimum, here defined as the fertilization level where each extra kg of fertilizer N resulted in a 10 kg increase in grain yield (85% DM). There were no statistically significant differences in leaching between treatments fertilized below this level. However, N leaching was significantly elevated in some of the treatments with higher fertilization rates and the increase in nitrate leaching from increased N fertilization could be described with an exponential function. According to this function, the increase was <0.04 kg kg−1 fertilizer N at and below the economic optimum. Above this fertilization level, the nitrate leaching response gradually increased as the yield response ceased and the increase amounted to 0.1 and 0.5 kg kg−1 when the economic optimum was exceeded by 35 and 100 kg N ha−1, respectively. The economic optimum fertilization level depends on the price relationship between grain and fertilizer, which in Sweden can vary between 5:1 and 15:1. In other words, precision fertilization that provides no more or no less than a 10 kg increase in grain yield per kg extra N fertilizer can be optimal for both crop profitability and the environment. To predict this level already at fertilization is a great challenge, and it could be argued that rates should be kept down further to ensure that they are not exceeded due to overestimation of the optimum rate. However, the development of precision agriculture with new tools for prediction may reduce this risk. 相似文献
5.
《European Journal of Agronomy》2007,26(4):372-382
Sustainable soil and crop management practices that reduce soil erosion and nitrogen (N) leaching, conserve soil organic matter, and optimize cotton and sorghum yields still remain a challenge. We examined the influence of three tillage practices (no-till, strip till and chisel till), four cover crops {legume [hairy vetch (Vicia villosa Roth)], nonlegume [rye (Secaele cereale L.)], vetch/rye biculture and winter weeds or no cover crop}, and three N fertilization rates (0, 60–65 and 120–130 kg N ha−1) on soil inorganic N content at the 0–30 cm depth and yields and N uptake of cotton (Gossypium hirsutum L.) and sorghum [Sorghum bicolor (L.) Moench]. A field experiment was conducted on Dothan sandy loam (fine-loamy, siliceous, thermic, Plinthic Paleudults) from 1999 to 2002 in Georgia, USA. Nitrogen supplied by cover crops was greater with vetch and vetch/rye biculture than with rye and weeds. Soil inorganic N at the 0–10 and 10–30 cm depths increased with increasing N rate and were greater with vetch than with rye and weeds in April 2000 and 2002. Inorganic N at 0–10 cm was also greater with vetch than with rye in no-till, greater with vetch/rye than with rye and weeds in strip till, and greater with vetch than with rye and weeds in chisel till. In 2000, cotton lint yield and N uptake were greater in no-till with rye or 60 kg N ha−1 than in other treatments, but biomass (stems + leaves) yield and N uptake were greater with vetch and vetch/rye than with rye or weeds, and greater with 60 and 120 than with 0 kg N ha−1. In 2001, sorghum grain yield, biomass yield, and N uptake were greater in strip till and chisel till than in no-till, and greater in vetch and vetch/rye with or without N than in rye and weeds with 0 or 65 kg N ha−1. In 2002, cotton lint yield and N uptake were greater in chisel till, rye and weeds with 0 or 60 kg N ha−1 than in other treatments, but biomass N uptake was greater in vetch/rye with 60 kg N ha−1 than in rye and weeds with 0 or 60 kg N ha−1. Increased N supplied by hairy vetch or 120–130 kg N ha−1 increased soil N availability, sorghum grain yield, cotton and sorghum biomass yields, and N uptake but decreased cotton lint yield and lint N uptake compared with rye, weeds or 0 kg N ha−1. Cotton and sorghum yields and N uptake can be optimized and potentials for soil erosion and N leaching can be reduced by using conservation tillage, such as no-till or strip till, with vetch/rye biculture cover crop and 60–65 kg N ha−1. The results can be applied in regions where cover crops can be grown in the winter to reduce soil erosion and N leaching and where tillage intensity and N fertilization rates can be minimized to reduce the costs of energy requirement for tillage and N fertilization while optimizing crop production. 相似文献
6.
Poor soil and drought stress are common in semiarid areas of China, but maize has a high demand for nitrogen (N) and water. Maize production using the technique of double ridges and furrows mulched with plastic film are being rapidly adopted due to significant increases in yield and water use efficiency (WUE) in these areas. This paper studied N use and water balance of maize crops under double ridges and furrows mulched with plastic-film systems in a semiarid environment over four growing seasons from 2007 to 2010. To improve precipitation storage in the non-growing season, the whole-year plastic-film mulching technique was used. There were six treatments which had 0, 70, 140, 280, 420 or 560 kg N ha−1 applied in every year for maize. In April 2011, spring wheat was planted in flat plots without fertilizer or mulch following four years of maize cultivation. After four years, all treatments not only maintained soil water balance in the 0–200 cm soil layer but soil water content also increased in the 0–160 cm soil layer compared to values before maize sowing in April 2007. However, under similar precipitation and only one season of spring wheat, soil water content in the 0–160 cm soil layer sharply decreased in all treatments compared to values before sowing in April 2011. Over the four years of maize cultivation, average yield in all treatments ranged from 4071 to 6676 kg ha−1 and WUE ranged from 18.2 to 28.2 kg ha−1 mm−1. In 2011, the yield of spring wheat in all treatments ranged from 763 to 1260 kg ha−1 and WUE from 3.5 to 6.5 kg ha−1 mm−1. The potential maximum grain yield for maize was 6784 kg ha−1 with 360 kg N ha−1 applied for four years, but considerable NO3N accumulated in the soil profile. A lesser application (110 kg N ha−1) to this tillage system yielded in 82% of the maximum, increased nitrogen use efficiency and mitigated the risk of nitrogen loss from the system. This study suggests that double ridge–furrow and whole-year plastic-film mulching could sustain high grain yields in maize with approximately 110 kg N ha−1 and maintain soil water balance when annual precipitation is >273 mm in this semiarid environment. 相似文献
7.
Nowadays agricultural practices are based in the use of N fertilizers which can lead to environmental N losses. These losses can occur as nitrous oxide (N2O) emissions as result of the microbial processes of nitrification and denitrification. N2O together with carbon dioxide (CO2) and methane (CH4) are the strongest greenhouse gases (GHG) associated with agricultural soils. Nitrification inhibitors (NI) have been developed with the aim of decreasing fertilizer-induced N losses and increasing N efficiency. One of the most popular NI is the 3,4-dimethylpyrazol phosphate (DMPP) which have proven to be an advisable strategy to mitigate GHG emissions while maintaining crops yield. A new NI, 3,4-dimethylpyrazole succinic (DMPSA), has been developed. The objective of this study was to compare the impact of the new nitrification inhibitor DMPSA on greenhouse gases emissions, wheat yield and grain protein with respect to DMPP. For this purpose a field-experiment was carried out for two years. Fertilizer dose, with and without NIs, was 180 kg N ha−1 applied as ammonium sulphate (AS) split in two applications of 60 kg N ha−1 and 120 kg N ha−1, respectively. A single application of 180 kg N ha−1 of AS with NIs was also made. An unfertilized treatment was also included. The new nitrification inhibitor DMPSA reduces N2O emissions up to levels of the unfertilized control treatment maintaining the yield and its components. The DMPSA shows the same behavior as DMPP in relation to N2O fluxes, as well as wheat yield and quality. In spite of applying a double dose of N at stem elongation than at tillering, N2O losses from that period are lower than at tillering as a consequence of the influence of soil water content and temperature reducing the N2O/N2 ratio by denitrification. NI efficiency in reducing N2O losses is determined by the magnitude of the losses from the AS treatment. 相似文献
8.
《European Journal of Agronomy》2005,22(1):71-84
Different preceding crops interact with almost all husbandry and have a major effect on crop yields. In order to quantify the yield response of winter wheat, a field trial with different preceding crop combinations (oilseed rape (OSR)–OSR–OSR–wheat–wheat–wheat), two sowing dates (mid/end of September, mid/end of October) and 16 mineral nitrogen (N) treatments (80–320 kg N ha−1) during 1993/1994–1998/1999, was carried out at Hohenschulen Experimental Station near Kiel in NW Germany. Single plant biomass, tiller numbers m−2, biomass m−2, grain yield and yield components at harvest were investigated. During the growing season, the incidence of root rot (Gaeumannomyces graminis) was observed. Additionally, a bioassay with Lemna minor was used to identify the presence of allelochemicals in the soil after different preceding crops.Averaged over all years and all other treatments, wheat following OSR achieved nearly 9.5 t ha−1, whereas the second wheat crop following wheat yielded about 0.9 t ha−1 and the third wheat crop following 2 years of wheat about 1.9 t ha−1 less compared with wheat after OSR. A delay of the sowing date only marginally decreased grain yield by 0.2 t ha−1. Nitrogen fertilization increased grain yield after all preceding crop combinations, but at different levels. Wheat grown after OSR reached its maximum yield of 9.7 t ha−1 with 210 kg N ha−1. The third wheat crop required a N amount of 270 kg N ha−1 to achieve its yield maximum of 8.0 t ha−1.Yield losses were mainly caused by a lower ear density and a reduced thousand grain weight. About 4 weeks after plant establishment, single wheat plants following OSR accumulated more biomass compared to plants grown after wheat. Plants from the third wheat crop were smallest. This range of the preceding crop combinations was similar at all sampling dates throughout the growing season.Root rot occurred only at a low level and was excluded to cause the yield losses. The Lemna bioassay suggested the presence of allelochemicals, which might have been one reason for the poor single plant development in autumn.An increased N fertilization compensated for the lower number of ears m−2 and partly reduced the yield losses due to the unfavorable preceding crop combination. However, it was not possible to completely compensate for the detrimental influences of an unfavorable preceding crop on the grain yield of the subsequent wheat crop. 相似文献
9.
Regions in north-western Europe characterized by high density of livestock/biogas plants and extensive silage maize production are facing major environmental challenges due to excessive residual soil mineral nitrogen (N) in autumn and hence nitrate leaching. Winter catch crops (CC) have potential to accumulate residual N; however, the N uptake potential after maize harvest in autumn and spring remains unclear. Therefore, a two-year field trial (April 2012–April 2014) was conducted at three sites, to quantify the combined effects of four consecutive CC sowing dates (10 Sep; 20 Sep; 30 Sep and 15 Oct) and two CC species (rye, Secale cereale. L. and Italian ryegrass, Lolium multiflorum Lam.) on DM accumulation and N uptake of CC above- and belowground in autumn and spring, and to derive functional relationships. The results clearly showed that rye was more effective in accumulating biomass and nitrogen than Italian ryegrass. The better performance of rye was related to increased growth intensity of roots and shoot, a different allocation pattern and higher N uptake efficiency. An exponential function of temperature sum (Tsum) produced a reliable prediction of above- and belowground biomass and N. To achieve an agronomically relevant N uptake of 20 kg N ha−1, rye required 278 °Cd Tsum, which corresponds to a sowing date latest in the second decade of September. Under favourable growing conditions, a biomass accumulation of up to 5 Mg DM ha−1, corresponding to 83 kg N ha−1 above- and belowground, seems achievable under the given environmental conditions. In continuous maize grown under the environmental conditions of Northern Germany, however, catch crops will not reach a relevant N uptake on the long-term average. 相似文献
10.
The expansion of biogas feedstock cultivation may affect a number of ecosystem processes and ecosystem services, and temporal and spatial dimensions of its environmental impact are subject to a critical debate. However, there are hardly any comprehensive studies available on the impact of biogas feedstock production on the different components of nitrogen (N) balance. The objectives of the current study were (i) to investigate the short-term effects of crop substrate cultivation on the N flows in terms of a N balance and its components (N fertilization, N deposition, N leaching, NH3 emission, N2O emission, N recovery in harvested product) for different cropping systems, N fertilizer types and a wide range of N rate, and (ii) to quantify the N footprint of feedstock production in terms of potential N loss per unit of methane produced. In 2007/08 and 2008/09, two field experiments were conducted at two sites in Northern Germany differing in soil quality, where continuous maize (R1), maize–whole crop wheat followed by Italian ryegrass as a double crop (R2), and maize–grain wheat followed by mustard as a catch crop (R3) were grown on Site 1 (sandy loam), and R1 and a perennial ryegrass ley (R4) at Site 2 (sandy soil rich in organic matter). Crops were supplied with varying amounts of N (0–360 kg N ha−1, ryegrass: 0–480 kg N ha−1) supplied as biogas digestate, cattle slurry, pig slurry or calcium-ammonium nitrate (CAN).Mineral-N fertilization of maize-based rotations resulted in negative N balances at N input for maximum yield (Nopt), with R2 having slightly less negative balances than R1 and R3. In contrast, N balances were close to zero for cattle slurry or digestate treatments. Thus, trade-offs between substrate feedstock production and changes of soil organic matter stocks have to be taken into consideration when evaluating biogas production systems. Nitrogen losses were generally dominated by N leaching, whereas for the organically fertilized perennial ryegrass ley the ammonia emission accounted for the largest proportion. Nitrogen balance of the ryegrass ley at Nopt was close to zero (CAN) or highly positive (cattle slurry, digestate). Nitrogen footprint (NFP) was applied as an eco-efficiency measure of N-loss potential (difference of N input and N recovery) related to the unit methane produced. NFP ranged between −11 and +6 kg N per 1000 m3 methane at Nopt for maize-based rotations, without a significant impact of cropping system or N fertilizer type. However, for perennial ryegrass ley, NFP increased up to 65 kg N per 1000 m3. The loose relation between NFP and observed N losses suggests only limited suitability for NFP. 相似文献
11.
In areas of Southern Europe with very intensive pig production, most of the pig slurry (PS) is applied as fertilizer. However, in the European Union, no more than 170 kg N ha−1 year−1 can be applied in nitrate vulnerable zones (NVZs) from livestock manures. In this context, a six-year trial was conducted for a maize-triticale double-annual forage cropping rotation under rainfed conditions. Four different N rates were applied (0, 170, 250 and 330 kg N ha−1 year−1), to evaluate their effect on crop yield, N uptake, unrecovered N and soil nitrate content. The corresponding PS rates were defined as zero (PS 0), low (PSL) medium (PSM) and high (PSH). The annual average dry matter (DM) yields (maize + triticale) for the PS fertilization treatments PS0, PSL, PSM and PSH were 12.6, 17.7, 20.2 and 22.0 Mg DM ha−1, respectively. Maize DM yield was influenced mainly by weather conditions, and triticale DM yield was clearly influenced by initial soil NO3−-N and PS fertilization rates. Unrecovered N was affected by PS fertilization rate and initial soil NO3−-N content. A residual effect of the PS when applied to maize had an important effect on soil NO3−-N and subsequent triticale DM yield. Moreover, total annual average unrecovered N, considering the sum of both crops (maize + triticale), were 91, 144, and 222 kg N ha−1 in PSL, PSM and PSH, respectively. In order to avoid part of this unrecovered N, mainly by lixiviation of nitrates, PS fertilization in triticale should be applied as side dressing at tillering. The application of N, in the form of PS, at rates higher than the legally permitted maximum of 170 kg N ha−1 year−1, may result in better yields. However, high rates of PS fertilization may originate in significantly lower N use efficiency and a higher potential environmental impact in double-cropping systems, practiced in rainfed sub-humid Mediterranean conditions. 相似文献
12.
《European Journal of Agronomy》2000,12(1):37-54
APSIM Nwheat is a crop system simulation model, consisting of modules that incorporate aspects of soil water, nitrogen (N), crop residues, and crop growth and development. The model was applied to simulate above- and below-ground growth, grain yield, water and N uptake, and soil water and soil N of wheat crops in the Netherlands. Model outputs were compared with detailed measurements of field experiments from three locations with two different soil types. The experiments covered two seasons and a range of N-fertiliser applications. The overall APSIM Nwheat model simulations of soil mineral N, N uptake, shoot growth, phenology, kernels m−2, specific grain weight and grain N were acceptable. Grain yields (dry weight) and grain protein concentrations were well simulated with a root mean square deviation (RMSD) of 0.8 t ha−1 and 1.6 protein%, respectively. Additionally, the model simulations were compared with grain yields from a long-term winter wheat experiment with different N applications, two additional N experiments and regional grain yield records. The model reproduced the general effects of N treatments on yields. Simulations showed a good consistency with the higher yields of the long-term experiment, but overpredicted the lower yields. Simulations and earlier regional yields differed, but they showed uniformity for the last decade.In a simulation experiment, the APSIM Nwheat model was used with historical weather data to study the relationship between rate and timing of N fertiliser and grain yield, grain protein and soil residual N. A median grain yield of 4.5 t ha−1 was achieved without applying fertiliser, utilising mineral soil N from previous seasons, from mineralisation and N deposition. Application of N fertiliser in February to increase soil mineral N to 140 kg N ha−1 improved the median yield to 7.8 t ha−1 but had little effect on grain protein concentration with a range of 8–10%. Nitrogen applications at tillering and the beginning of stem elongation further increased grain yield and in particular grain protein, but did not affect soil residual N, except in a year with low rainfall during stem elongation. A late N application at flag leaf stage increased grain protein content by several per cent. This increase had only a small effect on grain yield and did not increase soil residual N with up to 40 kg N ha−1 applied, except when N uptake was limited by low rainfall in the period after the flag leaf stage. The economic and environmental optima in winter wheat were identified with up to 140 kg N ha−1 in February, 90 kg N ha−1 between tillering and beginning of stem elongation and 40 kg N ha−1 at flag leaf stage resulting in a median of 8.5 t ha−1 grain yield, 14.0% grain protein and 13 kg N ha−1 soil residual N after the harvest. The maximum simulated yield with maximum N input from two locations in the Netherlands was 9.9 t ha−1. 相似文献
13.
In organic agriculture, weeds and nitrogen deficiency are the main factors that limit crop production. The use of relay-intercropped forage legumes may be a way of providing ecological services such as weed control, increasing N availability in the cropping system thanks to N fixation, reducing N leaching and supplying nitrogen to the following crop. However, these ecological services can vary considerably depending on the growing conditions. The aim of this study was to identify early indicators to assess these two ecological services, thereby giving farmers time to adjust the management of both the cover crop and of the following crop.Nine field experiments were conducted over a period of three years. In each experiment, winter wheat was grown as sole crop or intercropped with one of two species of forage legumes; Trifolium repens L. or Trifolium pratense L. Two levels of fertilization were also tested (0 and 100 kg N ha−1). After the intercropping stage, the cover crop was maintained until the end of winter and then destroyed by plowing before maize was sown. Legume and weed biomass, nitrogen content and accumulation were monitored from legume sowing to cover destruction.Our results showed that a minimum threshold of about 2 t ha−1 biomass in the aboveground parts of the cover crop was needed to decrease weed infestation by 90% in early September and to ensure weed control up to December. The increase in nitrogen in the following maize crop was also correlated with the legume biomass in early September. The gain in nitrogen in maize (the following crop) was correlated with legume biomass in early September, with a minimum gain of 60 kg N ha−1 as soon as legume biomass reached more than 2 t ha−1.Legume biomass in early September thus appears to be a good indicator to predict weed control in December as well as the nitrogen released to the following crop. The indicator can be used by farmers as a management tool for both the cover crop and following cash crop. Early estimation of available nitrogen after the destruction of the forage legume can be used to adjust the supply of nitrogen fertilizer to the following crop. 相似文献
14.
In dryland agricultural systems, pig slurry (PS) is usually applied to cereal crops only at sowing, and slurries accumulate for the rest of the year in pits. In this context, a four-year experiment was established in order to evaluate the feasibility of PS applications at the barley or wheat tillering stage. The main treatments were PS either applied at sowing (25 Mg ha−1) or not, but they alternated after a two-year period. Both were annually combined with eight side-dressing treatments at cereal tillering: mineral N as NH4NO3 (M; 60 or 120 kg N ha−1 yr−1), PS from fattening pigs (PSf; 17, 30, 54 Mg ha−1 yr−1), PS from sows (PSs; 25, 45, 81 Mg ha−1 yr−1) and a treatment without N. The combined fertilization treatments were 18 plus a control (no N applied). In the context of crop rotation, the biennial alternation of PS applied at sowing allowed the control of soil nitrate increments, while PS side-dressing improved N recovery compared with a unique application at sowing. The highest yields (>3.6 Mg ha−1 yr−1) were obtained with an annual average (4-yr) N rate close to 173 kg N ha−1 (±40 kg N ha−1). The best overall strategies corresponded to PSs side-dressings of 50–90 kg N ha−1. These PSs rates also recorded the highest values on the five calculated N-efficiency indexes, which were higher than or similar to results from M side-dressings or those recorded in the literature. These similarities (M vs. PSs) were also shown by the reduction of unaccounted-for N inside the overall N balance. Thus, split PS application during the crop cycle is a sound fertilization option in dryland systems. 相似文献
15.
This work was aimed at providing a sustainable approach in the use of manure in irrigated maize crop under Mediterranean climatic conditions. To this end, the effect of continuous annual applications of dairy cattle manure, combined or not with mineral N fertilizer, on the following parameters was studied: grain yield, grain and plant N concentration, N uptake by plant, N use efficiency, and soil N and organic carbon. The experiment was conducted in a furrow-irrigated sandy soil under dry Mediterranean conditions during seven years. Three different rates of cattle manure (CM): 0, 30 and 60 Mg ha−1, were applied each year before sowing. These CM rates were combined with four mineral N rates (0, 100, 200 and 300 kg N ha−1) applied at sidedress.On average, the highest grain yields during the 7 years were obtained with the combination of CM at 30 Mg ha−1 and mineral fertilizer and with CM at 60 Mg ha−1 without mineral fertilizer. With CM at 30 Mg ha−1, mineral fertilizer increased yields during most of the growing seasons, meanwhile with CM at 60 Mg ha−1, there was not any significant effect of the joint application of mineral fertilizer on yields. Overall, best results were obtained exceeding maximum rates according to present legislation. The mean apparent nitrogen recovery (ANR) fraction during the 7 seasons was 29% for N exclusively applied as CM. Overall, increased N rates applied as CM resulted in decreased ANRs. However, ANR with CM at 30 and 60 Mg ha−1 increased during the first two seasons. This increased ANR ascribed to mineralization of residual organic N applied in previous seasons explained the increasing yields observed in the treatments along the study.The application of CM during 7 years increased the soil organic carbon in the first 30 cm by 5.7 and 9.9 Mg ha−1 with CM at 30 and 60 Mg ha−1, respectively, when compared to the initial stock. Thus, manure-based fertilization could be an alternative to mineral fertilizer in order to achieve high maize yields while improving soil quality under dry Mediterranean conditions. 相似文献
16.
To identify the best practice for nitrogen (N) fertilization of overwinter processing spinach, two field experiments were carried out in the Foggia plain (Southern Italy), one of the most vocated area for leafy vegetables production. The field trials were aimed to define and suggest the proper fertilizer dose, typology and the right time of application. Experiment 1 evaluated four N fertilizer doses (0, 150, 225, 300 kg ha−1) in a two-year field trial. Experiment 2 was aimed to assess the effect of the split distribution of prilled urea fertilizer in comparison with the application of nitrification inhibitor (DMPP) containing urea fertilizer, broadcasted at sowing.Spinach yield, yield quality (nitrate – NO3− – and carotenoids content), N-use efficiency and risk of soil nitrate (NO3−-N) leaching were evaluated. The processing spinach yielded 37.8 and 3.6 t ha−1 of fresh and dry yield, respectively (average of the two experiments). Fresh and dry yield among the fertilizing treatments were similar. Also the β-carotene and the lutein content of spinach leaves (19.5 and 38.1 mg kg−1, respectively) were not affected by the N fertilizer dose. Conversely, the N dose strongly influenced the NO3− content of the leafy vegetable tissues (1286 mg kg−1 on average, 58% lower than the limits imposed by the EC regulation). As expected, the different rainfall pattern influenced both the leaf NO3− content and the risk of soil NO3−-N leaching. The results achieved demonstrated that, in order to get a favorable trade-off, among yield, yield quality, N-use efficiency and environmental impact, the processing spinach growers of the Foggia plain area should be encouraged to apply 225 kg N ha−1 as maximum fertilization rate. Also, the split urea fertilizer application appeared as the more effective strategy for N fertilization of overwinter spinach in comparison with the use of the nitrification inhibitor containing urea fertilizer, being the last strategy not able to adequately match the N crop demand. 相似文献
17.
《European Journal of Agronomy》2005,22(1):95-100
In recent years, the cultivation of the pseudocereal species amaranth, quinoa, and buckwheat has gained rising attention. This study was undertaken to explore nitrogen (N) fertility requirements and nitrogen use efficiency of these species. For this purpose, a 2-year field experiment with N rates of 0, 80, and 120 kg N ha−1 for amaranth and quinoa and 0, 30, and 60 kg N ha−1 for buckwheat and two cultivars of each species was conducted.Grain yield of amaranth responded to N and ranged between 1986 and 2767 kg ha−1. Nitrogen utilization efficiency (NUtE) ranged from 13.9 to 15.4 kg grain yield per kg above-ground plant N and decreased with increasing N rate. Higher grain yields and NUtEs seemed to be mainly inhibited by the low harvest index (0.22–0.23) of the investigated amaranth cultivars.Quinoa yielded between 1790 and 3495 kg grain ha−1 and responded strongly to N fertilization. NUtE averaged 22.2 kg kg−1 and did not decrease with increasing N rates.The grain yield of buckwheat did not respond to N fertilization and averaged 1425 kg ha−1. N uptake increased only slightly with N fertilization. NUtE ranged from 16.1 to 20.0 kg kg−1. Main problems occurring with the application of N to buckwheat were grain scattering and lodging. 相似文献
18.
The efficient use by crops of nitrogen from manures is an agronomic and environmental issue, mainly in double-annual forage cropping systems linked to livestock production. A six-year trial was conducted for a biennial rotation of four forage crops: oat-sorghum (first year) and ryegrass-maize (second year) in a humid Mediterranean area. Ten fertilization treatments were introduced: a control (without N); two minerals equivalent to 250 kg N ha−1 year−1 applied at sowing or as sidedressing; dairy cattle manure at a rate of 170, 250 and 500 kg N ha−1 year−1 and four treatments where the two lowest manure rates were supplemented with 80 or 160 kg mineral N ha−1 year−1. They were distributed according to a randomized block design with three blocks. The highest N mineral soil content was found in the summer of the third rotation, in plots where no manure was applied. The yearly incorporation of manure reduced, in successive cropping seasons, the amount of additional mineral N needed as sidedressing to achieve the highest yields. Besides, in the last two years, there was no need for mineral N application for the manure rate of 250 kg N ha−1 year−1. This amount always covered the oat-sorghum N uptake. In the ryegrass-maize sequence uptakes were as high as 336 kg N ha−1 year−1. In the medium term, the intermediate manure rate (250 kg N ha−1 year−1) optimizes nutrient recycling within the farming system, and it should be considered in the analysis of thresholds for N of organic origin to be applied to systems with high N demand. 相似文献
19.
Cover crops in dry regions have been often limited by low nutrient and water-use efficiency. This study was conducted during 3.5 years to determine the effect of replacing bare fallow by a cover crop on yield, N uptake, and fate of labeled fertiliser in an intensive maize production system. Three treatments were studied: barley (Hordeum vulgare L.), vetch (Vicia villosa L.) and bare fallow during the intercropping period of maize (Zea mays L.). All treatments were irrigated and fertilised following the same procedure, and a microplot in each plot was established with 210 kg N ha?1 of double labeled ammonium nitrate. Crop yield and N uptake, soil mineral N (Nmin), and recovery of 15N in plant and soil were determined after maize harvest and killing the cover crop. Replacing bare fallow with cover crops did not affect subsequent maize yield but affected N uptake. Vetch increased N supply by legume residues after the second year, and the N content in grain by the third. Nitrogen recover from fertiliser was not affected by treatment and averaged 46%. Barley recovered more 15N during the autumn–winter period than vetch or fallow. Under representative conditions, average barley N content was 47, vetch 51, and spontaneous vegetation content 0.8 kg N ha?1. Recovery of 15N in barley comprised 19% of total N content in aerial biomass, while only 4% in vetch. Vetch enhaced soil 15N recovery more than other treatments, suggesting its presence in a fairly stable organic fraction unavailable for maize uptake or lost. Replacing bare fallow by a cover crop only reduced fertiliser losses in a year with abundant precipitation. Nevertheless, reduction in soil Nmin in vetch and bare fallow treatments was similar, showing that N losses can be reduced in this cropping system, either by replace bare fallow with barley or smaller N fertiliser applicationto maize. 相似文献
20.
《European Journal of Agronomy》2007,26(2):166-177
In Jiangsu province, Southeast China, high irrigated rice yields (6–8000 kg ha−1) are supported by high nitrogen (N) fertilizer inputs (260–300 kg N ha−1) and low fertilizer N use efficiencies (recoveries of 30–35%). Improvement of fertilizer N use efficiency can increase farmers’ profitability and reduce negative environmental externalities. This paper combines field experimentation with simulation modeling to explore N fertilizer management strategies to realize high yields, while increasing N use efficiency. The rice growth model ORYZA2000 was parameterized and evaluated using data from field experiments carried out in Nanjing, China. ORYZA2000 satisfactorily simulated yield, crop biomass and crop N dynamics, and the model was applied to explore options for different N-fertilizer management regimes, at low and high levels of indigenous soil N supply, using 43 years of historical weather data.On average, yields of around 10–11,000 kg ha−1 were realized (simulated and in field experiments) with fertilizer N rates of around 200 kg ha−1. Higher fertilizer doses did not result in substantially higher yields, except under very favorable weather conditions when yields exceeding 13,000 kg ha−1 were calculated. At fertilizer rates of 150–200 kg ha−1, and at the tested indigenous soil N supplies of 0.6–0.9 kg ha−1 day−1, high fertilizer N recovery (53–56%), partial N productivity (50–70 kg kg−1) and agronomic N use efficiency (20–30 kg kg−1) were obtained with application in three equal splits at transplanting, panicle initiation and booting. Increasing the number of splits to six did not further increase yield or improve any of the N use efficiency parameters. 相似文献