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1.
不同土地利用方式对高寒地区水土流失的影响 总被引：1，自引：0，他引：1
通过对青藏高原边缘祁连山东段天祝金强河河谷不同土地利用方式下土壤的理化性质和水土流失状况的定点观测,分析了不同土地利用方式下的水土流失特征,探讨了不同土地利用方式对高寒地区水土流失的影响。结果表明：研究区的降雨量分布不均匀,不同土地利用方式下的径流量、泥沙量随降雨量变化存在显著差异(P＜0.05),径流量大小依次为：坡耕地(4199.96 mL)>退耕自然恢复地(3614.28 mL)>天然草地(1190.3 mL);泥沙流失量由大到小为：坡耕地(0.329 t/hm2)>退耕自然恢复地(0.256 t/hm2)>天然草地(0.087 t/hm2)。坡耕地和退耕自然恢复地径流量和泥沙流失量较大,水土流失较严重,天然草地在自然环境综合因素下进行更新,有利于防止土壤侵蚀,水土流失量比坡耕地和退耕自然恢复地小,水土保持效果较好。 相似文献
2.
David Fangueiro Jos Pereira Joo Coutinho Nuno Moreira Henrique Trindade 《European Journal of Agronomy》2008,28(4):625-634
Farm-gate nutrient balances (N, P and K) were analysed in three groups of dairy farms from NW Portugal – medium, intensive and very intensive farms – during 3 consecutive years, 2003, 2004 and 2005. Results showed that the N surplus per hectare with values between 200 and 850 kg N ha−1 was positively correlated with the milk production per ha and the stocking rate of the farm, whereas the P and K surpluses showed fewer variations between groups. In all farms the main inputs were the mineral fertilizers and the feed concentrates whereas milk was the main output. Farmers involved in the study were advised in terms of nutrient management and significant decreases in the nutrient surpluses were observed during the 3 years study, mainly due to a decrease of the inputs, namely fertilizers. We conclude that advisory campaigns among farmers are efficient to reduce the nutrient surpluses. The N losses via NH3 emissions at farm scale were also estimated accordingly to IPCC emission factors and it appeared that such losses were significant and had to be considered together with the nutrient surpluses when strategies to enhance nutrient management are defined. On average, higher N surplus per hectare were observed in the studied dairy farms from NW Portugal relatively to other European regions, but NW Portugal present lower N surplus per production unit (kg milk) as well as higher N efficiency. Nevertheless, a target limit of 450 kg N ha−1 for N surplus should be easily reached as a first step by most of the farms of NW Portugal by improving nutrient management at farm scale. However, more efforts will be necessary to reduce NPK surplus and NH3 emissions to the mean values in a per hectare basis found in other European dairy regions with less intensive systems. 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.
Kurt Mller 《European Journal of Agronomy》2009,31(4):204-212
Organic farming systems are characterized by the strong regulation of the import of nutrients into the farming system. Recently, nutrient budgets in organic farming especially with regard to potassium (K) and phosphorus (P) have gained interest. In the present study inner farm mineral nutrient flows of P, K and magnesium (Mg) among the farmland sub-compartments arable land and permanent grassland via the dairy stable were analysed. The objectives of the current study were (1) to quantify the inner farm nutrient flows among different farmland sub-compartments, and (2) to assess the effect of purchased biomass on inner farm nutrient cycles. Results indicated that the ratio of the nutrients N, P and K in the stable inputs (feed, bedding) greatly differed depending on the kind of biomass introduced into the stable (roughage in comparison to concentrates or straw for bedding), i.e. via grassland biomass much more K (7.9 kg) per kg P were introduced than with feeds harvested on arable land like silage maize (4.9 kg K per kg P), concentrates like cereals (1.3–1.6 kg K per kg P) or grain pulses like peas (2.4 kg K per kg P). The different inputs are mixed in the manures leading to intermediate concentration in the stable manures, with the consequence that nutrient composition of the manures does not match the composition of the single stable inputs. Therefore, balances of nutrient flows in such mixed systems indicate a relative transfer of K from grassland to arable land via the stable manure (approximately 10–30% of the manure derived from grassland K, depending among others on the amounts of straw high in K needed for animal bedding), if P was used as reference nutrient for stable manure allocation to permanent grassland and arable land. Yields of non-legumes in arable cropping in organic farming systems is very often limited by nitrogen (N) supply, whereas it is well known that manure additions are rather ineffective on permanent grassland high in legumes. The higher N demand of arable crops as well as P and K offtakes from arable land via sold animal and plant products give some scope for a preferable use of stable manures for manuring arable land to replace mineral nutrient outputs and to improve the soil N and the soil humus status, increasing the demand for supplement of mineral nutrients on the permanent grassland area to avoid long-term impoverishment of soil fertility. 相似文献
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中国农田退化价值损失计量研究 总被引：4，自引：0，他引：4
农田退化是全球普遍的问题,尤其是在亚非等发展中国家较严重,给农业发展带来巨大的经济损失。如何客观评价这些损失,本文利用市场价值、模拟市场价值、影子工程等方法开展评价研究。农田退化分为农田污染、生态破坏和肥力下降三个方面。其中农田污染计量了重金属和污灌污染造成的损失,生态破坏计量了土壤沙化、盐渍化和潜育化的损失,肥力下降是计量了生产力降低和水土流失的损失。研究结果表明：农田污染、功能降低以及肥力下降等退化类型价值损失量分别为440.51亿元、316.39亿元和468.55亿元。全国农田退化价值损失总量为1225.45亿元,分别相当于2004年GDP和农业国民生产总值的0.89%和6.20%。由此可见,农田退化对我国农业发展构成一定的影响,若不采取有效措施,将会对我国未来农业发展产生更大的影响。 相似文献
6.
In intensive integrated crop-livestock farming systems, the surplus of N at the farm scale may be large and reflects on the N balance at the field scale. A study was conducted to assess the N fertilizer efficiency in four private farms in intensively cropped areas of NW Italy, and to monitor the effects of agricultural practices on the mineral N concentration of the soil solution, sampled every 2 weeks for 2 years and considered as an indicator of potential leaching. Two cultivation systems were compared in each farm, one involving continuous maize rotation, the other assuring a continuous soil cover (permanent meadow or winter cereal-maize double cropping system). The fertilization level in the arable crops was high (369–509 kg N ha−1 year−1) compared to the crop removals, and resulted in a low efficiency, as indicated by the four examined efficiency indexes (calculated N surplus, N removal-fertilizer ratio, N apparent recovery, N use efficiency). The soil-water-nitrate concentration showed large temporal variations in the range of 1–150 mg l−1 for five out of the eight cropping situations, while concentrations smaller than 10 mg l−1 were always recorded in the meadows and in one of the four soils (Aeric epiaquept). The fertilizer management that characterized each cropping system affected the soil-mineral-nitrate content in shallow arable soils. The longer soil cover duration in double-cropping systems did not result in a reduction of soil N compared to maize as a single crop, not even in winter (the bare-soil intercropping period in maize-based systems). However, the temporal oscillations of the concentration were buffered by the crop cover duration and by the presence of a shallow water table (1 m deep) in the soil profile. The average nitrate content of the soil could be predicted by the N uptake of the crop, the N removal–fertilizer ratio, the soil pH and sand content, however no simple explanatory relationship was found with the experimental factors. Hence, in farm conditions, in the absence of sufficient data for a deterministic model approach, the target of reducing the risk of leaching should be achieved by maximizing the fertilizer efficiency. 相似文献
7.
黄土丘陵区退耕地景观植被与土壤特征时空变异及其相关分析 总被引：1，自引：0，他引：1
对黄土丘陵区退耕地景观不同尺度的植被特征中的物种丰富度、物种多样性、物种均匀度,土壤特征中的有机质、全N和全P含量的相关关系和时空格局进行了研究。结果表明：区域尺度退耕地的植被指数小于流域尺度,但具有更大的变异性。两种尺度上物种丰富度与物种均匀度之间、物种多样性与物种均匀度之间均存在接近显著或具有显著的正相关关系,有机质含量与全N含量之间存在着极显著的正相关关系。区域尺度和流域尺度退耕地的植被特征与土壤养分含量具有不同的时空格局,但并没有显著的相关关系。说明黄土丘陵区退耕地植被特征和土壤养分含量可能受控于别的环境因素或干扰过程,导致了其植被特征与土壤养分特征的时空差异性。 相似文献
8.
The effect of succeeding crop and level of N fertilization on N leaching after break-up of grassland
《European Journal of Agronomy》2009,30(4):200-207
Depending on soil and management, ploughing up grassland for use as arable land can lead to an increase in the release of mineralized nitrogen and a high risk of nitrogen leaching during winter. The amount of N leaching is also dependent on the N efficiency of following crops and the level of N fertilization.In a field experiment in northwest Germany permanent grassland was ploughed and used as arable land. The experiment was conducted over 2 years at three sites and investigated two main factors: (i) succeeding crops, either spring barley (and catch crop)–maize or silage maize–maize; and (ii) N-fertilization either nil or moderate (120 kg N ha−1 for barley or 160 kg for maize). Plant yields, the soil mineral nitrogen (SMN) content and the nitrate leaching losses over winter were determined. On average for the 2-year period, the SMN in autumn and the nitrate leaching losses during winter for the rotation barley–maize were 76 kg ha−1 SMN and 81 kg N ha−1 N leaching losses, and for maize–maize they amounted to 108 and 113 kg ha−1, respectively. The SMN and N leaching losses for the plots with no N fertilizer were 49 and 52 kg N ha−1 and for the plots fertilized at a moderate N level they were 135 and 142 kg N ha−1, respectively.We conclude that although the extent of nitrate leaching is influenced by the site conditions and management of the grassland prior to ploughing, the management after ploughing is the decisive factor. The farmer can significantly reduce nitrate leaching with his choice of succeeding crop and the amount of N fertilization. 相似文献
9.
C、N、P 是生物地球化学循环中的重要元素,在生态系统中占有重要地位,植物体内特别是叶片C、N、P 的生态化学计量学特征一直是生态学研究的一个热点。通过测定吉林省姜家甸草地不同退化演替阶段羊草叶片中C、N、P含量,研究了草地退化演替阶段羊草叶片生态化学计量特征。结果表明：C含量轻度退化草地最高,极严重退化草地最低;N含量极严重退化草地最高,未退化草地最低;P含量极严重退化草地最高,中度退化草地最低;C/N未退化草地最高,极严重退化草地最低;C/P 中度退化草地最高,极严重退化草地最低;N/P重度退化草地最高,未退化草地最低。未退化草地羊草受N和P共同限制,退化草地主要受P限制。生态化学计量学特征对草地不同退化演替阶段具有指示意义。 相似文献
10.
油稻轮作下有机无机肥配施对作物产量及氮磷流失的影响 总被引：2，自引：1，他引：1
通过油稻轮作田间试验,研究了等养分条件下4种施肥处理对作物产量、地表径流N、P流失浓度和流失量及其对环境的影响。试验设4个处理,即:化肥(CF)、化肥+低量有机肥(OC1)、化肥+中量有机肥(OC2)、化肥+高量有机肥(OC3)。结果表明,与单施化肥相比,有机无机肥配施处理在满足作物养分需求,保持相对较高的产量水平基础上,能显著或明显减少农田径流水铵态N、硝态N和全P的流失浓度和流失量,尤以中、高量有机肥处理效果最显著;各处理径流液全N浓度范围在0.60~27.89mg/L,总P浓度范围在0.059~0.353mg/L,均大于富营养化水体标准,污染周边水环境;N流失指数明显高于P,且硝态N是N流失的主要形式;中高量有机肥与化肥配合施用能够保证作物产量,并能有效降低N、P的径流流失,为适宜该地区油稻轮作的合理施肥制度。 相似文献
11.
Agricultural systems will have to produce more and better in a changing world. Mixed crop livestock systems (MCLS) are sound alternative ways to progressively achieve these goals through crop-livestock integration (CLI). CLI exploits the synergies between cropping and livestock systems, for example, through organic fertilization and the use of crop residues to feed livestock, and offers many opportunities to improve productivity, as well as to increase resource use efficiency and improve the resilience of the whole farming system. In the scientific literature, authors advocate the interest of MLCS and CLI, based on theoretical considerations, modelling and empirical evidence from local case studies. But these studies do not clearly identify the respective roles of the diversity of activities and CLI management practices in improving performances at the level of the whole farming system. The aim of this study was thus to assess CLI at farm scale in a range of MCLS and to explain farm performances by analyzing the combination of activities and the level of integration. This study was conducted in Guadeloupe, (French West Indies), where MCLS and CLI are complex but important challenges for local agricultural. Ecological network analysis was used to study the structure, functioning and performance of agrosystems. To this end, a range of eight farms was selected to characterize CLI as practices, and as a network of nitrogen flows at farm level. The land and labor productivity were then assessed along with the resilience, efficiency, productivity and self-sufficiency of the network of flows. Results show that CLI only applies to certain types of production, including feeding pigs with a wide range of crop residues (crop residues provide from 16 to 45% of the N supply to pigs) or organic fertilization of small market gardens and plots used to grow tubers (manure provides 24–100% of the N supply to plots). But at whole system level, CLI remains low: in seven cases, the N circulating within the system – ICR- represent only between 0.7 to 3.5% of the total N circulating through the system; only one farm presents a higher intensity of CLI, with an ICR of 18.9%. Consequently, performances and especially efficiency and productivity, depend more on the nature of the activity than on CLI management practices. 相似文献
12.
日本和美国社区支持型农业的发展及其启示 总被引：7，自引：1，他引：6
社区支持型农业(CSA)是可持续农业的重要形式之一,近几年在国内逐渐受到人们关注,为借鉴日本和美国CSA发展的经验教训,促进中国CSA健康发展和城乡互补。为此,重点介绍了CSA在两国的发展历程及趋势,分析了兴衰背后的社会原因及其启示,并探讨了中国发展社区支持农业的潜在需求。研究得出：CSA最早产生的日本,随着有机农场的减少,以及社会经济变化等原因,CSA已经变得日益衰落;而在其后CSA兴起的美国却迎合了广大民众的需求得以蓬勃发展,并且功能形式日趋灵活多样,农场平均规模趋于减小。CSA的兴起和发展与其社会背景紧密相关,CSA多数提倡采用机生产方式同时兼备多种功能,其发展遵循平等互利、规模适度等原则,外部支援和参与有助于增强其发展活力。这对中国CSA和持续农业发展具有借鉴意义。该文从维护农民利益、保障市民需求及城乡一体化等角度,认为CSA是中国发展可持续农业、实现城乡协调发展的一条“绿色通道”。 相似文献
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M. J. Zijp 《Euphytica》1953,2(1):62-71
Summary A factor of utmost importance to the breeder of grasses and clovers is the clear formulation of the problem, which types should be selected. This is closely correlated with the way the grassland is managed. A comparison of the methods of management used in Denmark, England, New Zealand and the Netherlands has been made. At the same time an account is given of the types of grasses and clovers that resulted from the application of these methods.It is probable that in the near future the importance of perennial ryegrass in the Netherlands will still increase. In the connection 7 characters of importance in breeding work with this species are given, as well as the consequences of the systems of management for some other grasses and white clover.Finally a close cooperation has been suggested between all those interested in improving the yield of grassland. 相似文献
16.
为探究抚仙湖流域植烟区烤烟适宜施氮量,减少烟田径流氮磷流失,通过田间试验研究了不同施氮(N)水平(N0：0 kg/hm2、N60：60 kg/hm2、N75：75 kg/hm2、N90：90 kg/hm2、N105：105 kg/hm2)对植烟区农田地表径流氮磷流失、烤烟(Nicotiana tabacum)氮素吸收利用和经济性状的影响。结果表明：（1）随着氮肥施用量增加,地表径流总氮(TN)和总磷(TP)浓度及其流失量逐渐升高;（2）与常规施氮处理(N105)相比,N60、N75、N90处理径流TN和TP平均浓度分别降低18.6%、14.7%、9.15%和12.3%、7.66%、5.25%,TN和TP流失总量分别降低19.2%、18.1%、9.81%和14.4%、10.1%、6.78%;（3）烟株氮累积量随施氮量的增加而增加,氮肥利用率呈先上升后下降趋势,以处理N75的氮肥利用率最高,为27.00%;氮肥偏生产力随着施氮水平的提高而显著下降(P<0.05);（4）烤烟产量随施氮量提高而增加,施氮处理较N0处理增产3.02%~13.90%,上等烟、上中等烟比例、产值和均价,随施氮量增加呈先上升后下降趋势,以施氮量75 kg/hm2的效果最佳。综合考虑烤烟经济性状及环境效益,N75处理既可提高烤烟经济性状,又能有效降低植烟区氮磷流失风险。 相似文献
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N.J. Hoekstra R.P.O. Schulte P.C. Struik E.A. Lantinga 《European Journal of Agronomy》2007,26(4):363-374
Livestock production has been identified as a major source of nitrogen (N) losses. Therefore, it is important to reduce N output through animal excretions by improving N utilisation by the animal. The objective of this paper is to identify pathways for producing grass-based diets that maximise bovine N utilisation during grazing, based on literature on the interface of plant and animal sciences. The focus is on Western-European perennial ryegrass-based systems under rotational grazing and both beef and dairy production systems are considered.
Three pathways have been identified through which more efficient N utilisation by grazing bovines can be achieved by manipulation of the chemical composition of the grass forage: (1) matching protein supply to animal requirements, (2) balancing and synchronising carbohydrate and N supply in the rumen, and (3) increasing the proportion of rumen undegradable protein (RUP).
Matching the diet requirements of grazing bovines through herbage manipulation encompasses the manipulation of carbon (C) and nitrogen (N) contents of growing herbage. These C and N contents vary both spatially within the grass sward and over time. Under grazing conditions, grassland management tools, such as the length of the regrowth period, grazing intensity, fertiliser N application rate and herbage variety are the main pathways to manipulate C and N dynamics. Regrowth length, N application rate and high sugar varieties were shown to be the most promising grassland management tools with respect to manipulating herbage quality and subsequent bovine N efficiency. However, these management tools are interrelated and may show adverse effects on production.
Due to the complex nature of interactions, modelling is essential in order to quantify and predict the effect of any combination of herbage management tools under specific circumstances.
Areas in which additional research is required are the fractionation of N compounds in herbage as affected by herbage management, and the effect of high sugar varieties on bovine N efficiency under a range of herbage management combinations. 相似文献
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T. Haase C. Schüler H.-P. Piepho H. Thöni J. Heß 《Journal of Agronomy and Crop Science》2007,193(4):270-291
Factorial field trials were carried out on an experimental farm near Kassel, Germany, in two consecutive seasons (2003 and 2004) in order to examine the impact of leguminous and cereal preceding crops (i) on soil N availability under subsequent potatoes and (ii) the effect of preceding crop and pre‐sprouting of seed tubers on crop development, N uptake, N utilization efficiency and total and size‐graded tuber yields relevant for processing into either crisps or French fries. In addition, an approach to analyse complex field experiments using mixed models is discussed. Soil mineralized nitrate‐N at emergence of the potato crop was affected by the preceding crop and was highest when potatoes followed peas, while the short‐term alfalfa/grass/clover ley appeared too sensitive to environmental conditions in the preceding cropping season, and its efficiency in terms of N supply may be hard to predict. Pre‐sprouting advanced crop development and dry matter accumulation of the canopy, translocation of assimilates and N from canopy into tubers and allowed an increased N utilization efficiency. The positive effect of pre‐sprouting on total tuber yield was compensated up to the final harvest, but a higher percentage of marketable tuber yield for French fries (>50 mm) was found independently of the date of harvest. An increasing N supply (after peas and a following catch crop) may be efficient in terms of higher yields of the marketable size‐grades (40–65 mm) for crisps, but increase oversized tuber yields in seasons not affected by Phytophthora infestans. Average tuber fresh weight responded consistently and positively to seed‐tuber preparation (pre‐sprouting), cultivar (cv. Agria) and an increased N supply (after peas). 相似文献
20.
为阐明中梁山岩溶槽谷区不同土地类型土壤养分的空间分布特征及其影响因素,运用地统计学理论和实验室分析方法,以中梁山槽谷区典型耕地、荒草地和林地为研究对象,分析不同土地类型、不同土层深度(0~15、15~30、30~45 cm)土壤有机碳(SOC)、全氮(TN)和全磷(TP)空间分布规律和生态化学计量学特征。结果表明：3种土地类型土壤SOC、TN和TP含量的平均值分别为20587.8、1472.8、598.9 mg/kg,SOC和TN空间变异性较大,TP变异性较小。土壤C、N、P含量随土层深度的增加而降低。SOC、TN含量为：林地＞荒草地＞耕地;TP 含量为：耕地＞荒草地＞林地。土壤C/N、C/P 和N/P 空间变异较大（变异系数CV＞28%）,C/N值变化范围为5.04~41.2,平均值为14.1;C/P 值变化范围为11.02~105.42,平均值为37.28;N/P 值的变化范围为0.99~6.32,平均值为2.71。不同土地类型土壤C/N 差异不显著,C/P、N/P值差异显著。C/N 值为林地＞耕地＞荒草地,C/P、N/P 值为林地＞荒草地＞耕地。耕地土壤SOC、TN和TP之间有显著的相关关系(P＜0.01),线性拟合度较高;荒草地和林地的TN与TP、SOC与TP相关性不太明显,线性拟合度较低。C、N、P 含量及其生态化学计量值受土壤理化性质、土地类型和人类活动等因子影响。通过对土壤理化性质分析表明：土壤TN、SOC和碱解氮是影响土壤C/N、C/P 和N/P 值的主要因素。中梁山岩溶槽谷区土壤C、N、P含量和C/N/P 值受土地类型、土壤理化性质、人类活动等因素影响较为明显,空间变异性较大。在实际土地利用过程中,要根据不同类型土壤养分状况,因地制宜、科学合理的利用土地,减少土壤养分流失。 相似文献