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1.
In a 2-year field experiment (2002/2003) on a loess soil near Göttingen/Germany, pea (Pisum sativum L.) and oat (Avena sativa L.) were grown alone and intercropped at a range of densities. Shoot biomass, grain yields and amount of N in grain were evaluated and optimized using two different replacement series and a hyperbolic yield–density equation describing a response surface to address the following questions: (i) what is the optimal composition of the pea–oat intercrop with regard to maximum yields, (ii) which intercropping design is most suitable to describe competition effects in pea–oat intercrops and the optimal intercrop compositions and (iii) which intercropping design is best suited for the evaluation of field data. For (i), the optimal intercrop compositions varied depending on the growth conditions for the crops. Furthermore, optimal intercrop compositions were found above the recommended sole crop densities. The density of oat had to be reduced more than that of pea, especially when optimal grain-N yields were desired and soil-N content was high. For maximum grain-N yields, pea could be sown at high densities in combination with 5–50% of the recommended density of oat. Thus, density can be used as a yield regulator for specific purposes such as a high N yield. The effects of competition at final harvest were described equally by both designs (ii). Oat was the clearly stronger and pea the inferior competitor. In contrast to the replacement series design, the hyperbolic yield–density equation was capable of adding valuable information about the extent of intra and interspecific competition. As intraspecific competition was consistently more important than interspecific competition, resource complementarity could be hold responsible for intercrop advantages. The highest intercrop advantage was found when total intraspecific competition was low, as shown by the relative yield total (RYT) and niche differentiation index (NDI) values >1. However, due to the RYT dependence on sole crops and total densities, the replacement series design led to misleading interpretations of the yield advantages. Both experimental designs were able to describe the field-data reliably (iii), but the response surface design had the advantage of being unaffected by insufficient field emergences, as it is not based on total densities. Numbers of plants m−2 instead of seeds m−2 can be used for the evaluation. Data from sole crops are not needed for the response surface design and thus the feared high experimental effort of this design can be reduced. However, when using the replacement series design, experimental effort should be greater than normal, as different sole crop densities and more intercrop compositions within a replacement series can lead to a more precise interpretation of the competition effects. 相似文献
2.
《Field Crops Research》2001,72(3):185-196
Two field experiments were carried out on a temperate sandy loam using six pea (Pisum sativum L.) and five spring barley (Hordeum vulgare L.) cultivars to determine cultivar complementarity in the intercrop for grain yield, dry matter production and nitrogen (N) acquisition. Crops were grown with or without the supply of 40 or 50 kg N ha−1 in the two experiments. Cultivars were grown as sole crops (SC) and as mixed intercrops (IC) using a replacement design (50:50). The land equivalent ratio (LER), which is defined as the relative land area under SC that is required to produce the yields achieved in intercropping, were used to compare cultivar performance in intercropping relative to sole cropping.Barley was the stronger competitor in the intercrops and as a result barley grain yield and nitrogen uptake in IC were similar to SC. The per plant pea grain production and aboveground N accumulation in IC were reduced to less than half compared to SC pea plants due to competitive interactions.Application of N caused a dynamic change in the intercrop composition. Competition from barley increased with N application and the pea contribution to the combined intercrop grain yield decreased. The LER values showed that in the intercrop plant growth resources were used on average 20% more efficient without N application and 5–10% more efficient with N application.The choice of pea cultivar in the intercrop influenced the intercrop performance to a larger degree than the choice of barley cultivar. Furthermore, pea cultivar×cropping systems interactions was observed, indicating that cultivars performed differently in sole and intercrops. An indeterminate pea cultivar competed strongly with barley causing a greater proportion of peas in the intercrop yield, but caused a reduced N uptake and yield of barley. Determinate peas with normal leaves caused the highest degree of complementary use of N sources by allowing barley to exploit the soil N sources efficiently, while they contribute with fixed N2. However, difference in performance among cultivars was observed. Using the indeterminate pea cultivar combined IC grain yield was in general lower than the greatest sole crop yield and vice versa for the determinate pea cultivars. Up to 22% (LER=1.22) greater combined IC grain yield was observed in several mixtures using determinate pea cultivars.From the present study, it is was concluded that there is a need for breeding suitable pea cultivars for intercropping purposes, since cultivars bred for sole cropping may not be the types, which are the most suitable for intercropping. For optimized N-use in pea–barley intercrops it is concluded that important traits for the intercropped pea are: (1) determinate growth, (2) a medium competitive root system for soil inorganic N and other nutrients during early growth, (3) high light absorption capacity by peas growing underneath the canopy of the higher barley component and (4) early establishment of symbiotic N2 fixation to support a high growth rate during early growth stages.Fertilized pea–barley intercrops gave a 15% higher net income than fertilized barley sole cropping and is regarded as a better safeguard for the farmer’s earnings compared to pea sole cropping known for variable yields and poor competitive ability towards weeds. 相似文献
3.
Effects of crop density and tillage system on grain yield and N uptake from soil and atmosphere of sole and intercropped pea and oat 总被引：1，自引：0，他引：1
Pea (Pisum sativum L.) and oat (Avena sativa L.) were grown as sole and mixed crops in various densities under two different tillage systems on a loess soil near Göttingen/Germany in a 2-year field experiment (2002/2003). In the conventional tillage system a mouldboard plough (CT) was used and in the minimum tillage system a rotary harrow (MT) was employed. The effect of crop density and tillage system on the grain dry matter and grain N yields, N2 fixation and soil N uptake were determined to address the following questions: (i) which mixture compositions exhibit the highest grain yields compared to the sole crops, (ii) which mixture compositions also fix a high level of N2 and leave low levels of residual inorganic soil N after harvest, and (iii) whether the intercrop advantage is influenced by the tillage system. For (i) the result in 2002 showed that the highest grain yields of both sole cropped pea and oat and intercropped pea and oat were achieved at the highest densities. In 2003, when the inorganic soil N content was higher and weather conditions were warmer and drier, grain yields were significantly higher than in 2002, but sole as well as intercropped pea and oat gave their highest grain yields at lower densities. For both years and tillage systems, the highest intercrop advantages were achieved in mixtures with densities above the optimal sole crop densities. The result for (ii) was that a distinctly higher proportion of nitrogen was derived from the atmosphere (Ndfa) by intercropped pea than by sole cropped pea. However, the uptake of soil N by intercropped pea and oat was not reduced in comparison with that of sole cropped oat as the decrease in the uptake of N from the soil by oat at lower oat densities in the mixture was compensated for by the soil N uptake of pea. Additionally, the Nmin-N content of the soil following the mixtures and sole cropped oat did not differ, especially in the deeper soil layers because oat in mixture was forced to take up more soil N from deeper layers. Therefore, the risk of soil N losses through leaching after mixtures was lower compared to sole cropped pea. The tillage system (iii) had no significant influence on grain yield and soil N uptake, but N2 fixation and the competitive ability of intercropped pea were higher under CT than with MT. An additional result was that intercropping led to a significantly increased grain N content of both pea and oat compared to the sole crops. The increase in grain N content from sole to intercrop was from 3.30 to 3.42% for pea and from 1.73 to 1.96% for oat as a mean for both years and tillage systems. The present study confirms that growing pea and oat as intercrops highlights potential economic and environmental benefits which still need to be understood in more detail in order to exploit intercropping to a greater extent. 相似文献
4.
5.
《Field Crops Research》1995,43(1):19-29
Lupin, field pea, lentil, chickpea, canola, linseed, and barley were sown at different times (late April-early July) to study their effects on subsequent wheat production on a red earth at Wagga Wagga, New South Wales. The cultivars of field pea (Pisum sativum) included Dunn, Derrimut, Maitland and Dinkum; narrow-leaf lupin (Lupinus angustifolius) cultivars were Danja, Geebung and Gungurru, and either the L. angustifolius line 75A/330 (1989–1990) or the broad-leaf lupin L. albus cv. Ultra (1991–1992). Only one cultivar of the other crops was grown in any year and after 1989 lentil (Lens culinaris cv. Aldinga) was replaced by chickpea (Cicer arietinum cv. Amethyst). The canola (cv. Shiralee (1989–1991), cv. Barossa (1992)) and linseed (cv. Glenelg) rotations received annual applications of 40–50 kg N/ha as urea.Compared to barley and the oilseeds, grain legumes increased soil mineral N supply to the following wheat crop. Over 4 years the mean wheat grain yield response to a broad-leaf crop, relative to barley, was 115% for lupin, 84% for field pea, 88% for linseed and 86% for canola. However, the effects of the various crops on subsequent wheat grain yields and grain protein varied markedly with season. The main advantage of lupin over field pea occurred in years when disease reduced growth of field pea crops. In high rainfall years, wheat yields following lentil and chickpea were lower than those following lupin. The narrow-leaf cultivars of lupin promoted greater wheat yields than either the reduced branching line 75A/330 or the broad-leaf albus cultivar Ultra. Delayed sowing of lupin reduced yield and grain protein of wheat, except when low rainfall curtailed growth of either crop in the rotation. There was little effect of field pea sowing date on wheat grain yield but sowing in late June combined with a dry spring, reduced mineral N supply and grain protein. Late sowing of oilseeds had no consistent effect on wheat grain yield but increased grain protein in most years. Late sowing of barley typically increased wheat grain yield but had little effect on grain protein. The effects of sowing time were mainly attributed to effects on soil N supply and for barley on disease incidence in the subsequent wheat. 相似文献
6.
The introduction of a living cover crop during a cash crop growth cycle (relay intercropping) and its maintenance after the cash crop harvest may help to preserve biodiversity, increase soil organic matter content and carbon sequestration and provide other ecosystem services, such as natural pest regulation or nutrient recycling, by increasing useful biotic interactions within the agroecosystem. We studied the impact of various approaches to manage a red fescue cover crop in a winter wheat crop in terms of light, water and nitrogen competition, using the STICS crop model adapted for intercropping. The STICS model for wheat/fescue intercropping was first evaluated on two years of experimental data obtained in the field. It gave satisfactory statistical results for the prediction of dry matter, leaf area index (LAI) and nitrogen accumulation in the two species, and for nitrogen and water dynamics in the soil. By simulating unmeasured variables, such as transpiration, the model improves our understanding of the performance of the intercrop in the field. For example, we showed that the intercropping system was more efficient that wheat grown as a sole crop, in terms of nitrogen accumulation and decreasing soil nitrogen levels before the leaching period. However, it also resulted in lower wheat yields. We then used the STICS model to compare four intercropping management scenarios differing in terms of the date of red fescue emergence, over 35 climatic years. We found that, in most climatic scenarios, the emergence of the fescue crop during the late tillering phase of the wheat crop gave the best compromise between wheat yield overall nitrogen accumulation and radiation interception. 相似文献
7.
Are seeding densities an opportunity to increase grain yield of winter wheat in a living mulch of white clover? 总被引：1，自引：0，他引：1
Optimum plant densities are a key to maximise yields in most crops. However, such information is often lacking for more environmentally sound cropping systems, such as living mulches (LM) for small grains. In 2004 and 2005, three trials were conducted in the Swiss Midlands on fields managed in accordance with the Swiss organic farming guidelines. The objective of the study was to determine whether seeding density of winter wheat (Triticum aestivum L.) is a relevant factor for determining grain yield in a white clover (Trifolium repens L.) living mulch. The winter wheat cv. Titlis was directly sown in wide spaced rows (0.375 m) at densities of 300 (LM300), 450 (LM450) or 600 (LM600) viable grains m−2 in a white clover living mulch established at a seeding rate of 15 kg ha−1. A bare soil control treatment with a wheat density of 450 viable grains m−2 (BS450) was also included in the trials. Mean grain yields of LM300, LM450, and LM600 never reached the values observed in BS450. This was mainly due to a lower ear density, which, nevertheless, increased linearly with the seeding density within the living mulch in all trials, but the rate of increase depended on the environment. The decrease of the grain weight brought about by the increasing seeding density had only a marginal impact on the grain yield, which was increased from 1.31, 1.98, and 4.09 Mg ha−1 (LM300) to 1.97, 2.64, and 4.75 Mg ha−1 (LM600) for each of the three trials in the study. Significantly higher protein contents were observed for LM300 compared to the higher densities in the living mulch and to BS450. Our research showed that an increase of the seeding density is an effective mean to increase the grain yield in living mulch systems with white clover. However, it is likely that the control of the living mulch to reduce competition with the main crop is a more relevant factor. 相似文献
8.
以马铃薯-大豆套作模式为研究对象,通过2年的大田试验,分析不同熟期大豆品种与马铃薯组合后系统内作物干物质和养分积累的特性与种间竞争补偿的相互关系,阐明间套作系统种间竞争力弱化和恢复补偿能力提高的作用机理,为实现间套作可持续发展提供科学依据。结果表明:套作马铃薯干物质及养分积累无显著变化,而套作大豆变化显著。出苗60 d内套作大豆干物质积累量是同期单作的43.74%,出苗后80～100 d,晚熟品种干物质积累量相对于中熟和早熟提高的幅度分别为35.54%～59.22%和65.56%～70.81%,大豆收获时,晚熟品种干物质积累接近单作,两者间差异不显著。共生期,套作大豆N、P、K积累量较同期单作降低的幅度分别为31.43%～41.44%、21.17%～25.36%和23.23%～35.6%,晚熟品种与中熟、早熟品种间差异达到显著水平。共生期结束后,套作大豆养分吸收量较单作显著增加,收获时,晚熟品种N、P、K养分积累量接近单作,两者间差异不显著。综上,在该群体中,马铃薯是核心作物,共生期处于竞争优势(APS>0、CRPS>0),而大豆处于竞争弱势(APS<0、CRPS<0),选择晚熟大豆品种与马铃薯组合可弱化种间竞争力和营养竞争比率,还有利于马铃薯收获后恢复补偿能力的发挥。 相似文献
9.
Water use and yield of wheat/maize intercropping under alternate irrigation in the oasis field of northwest China 总被引：1，自引：0，他引：1
A field experiment was carried out to investigate the effects of alternate irrigation (AI) on the yield, water use and water use efficiency (WUE) of wheat (Triticum aestivum L.)/maize (Zea mays L.) intercropping system in an oasis region of northwest China in 2006-2008. Three planting patterns, i.e., sole wheat, sole maize and wheat/maize intercropping. Three irrigation levels were applied for each treatment during 3 years. Results showed that land use efficiency of wheat and maize was significantly enhanced by intercropping system; land equivalent ratio (LER) of wheat/maize intercropping system in different treatments was all greater than 1.0. Moreover, significant difference in grain yield was observed between intercropping treatment and sole cropping treatment, in which the yield of intercropped wheat was 55.37-74.88% of sole wheat, and intercropped maize was 66.63-78.87% of sole maize. Wheat/maize intercropping treatments increased water use by 1.8-16.4% than half of the total water use of sole-cropping wheat and maize. Compared to sole cropping wheat treatments, wheat/maize intercropping with alternate irrigation significantly improved water use efficiency (WUE) by 30.5-57.7%, 55.5-71.4% and 12.0-19.8%, and increased by 32.7-37.8%, 9.5-15.8% and 4.0-20.8% than sole cropping maize treatments in 2006-2008, respectively. Our results suggest that AI should be a useful water-saving irrigation method on wheat/maize intercropping in arid oasis field where intercropping planting is decreased because of limited water resource. 相似文献
10.
In China, a large acreage of cultivated land is devoted to relay intercropping of winter wheat and cotton. Wheat is sown in strips with interspersed bare soil in October and harvested in June of the next year, while cotton is sown in the interspersed paths in the wheat crop in April and harvested before the next wheat sowing in October. This paper addresses the question how strip width and number of plant rows per strip of wheat or cotton affect light interception (LI) and light use efficiency (LUE) of both component crops. 相似文献
11.
《Plant Production Science》2013,16(1):39-46
AbstractField experiments were conducted to characterize intercropping advantages in groundnut-fingermillet intercrop in relation to crop combination ratios, soil moisture and nitrogen (N) availability. Three intercrops in 1 : 2, 1 : 1 and 2 : 1 alternating rows of groundnut and fingermillet were examined for their growth and yield in comparison with their respective sole crops in 1996. The effect of well watered (W) and water stressed (D) conditions on the intercropping advantage was also examined for 1 : 1 intercrops in 1995 and 1996. Fertilizer N was applied at the rate of 20 kg ha?1 in 1995 and 50 kg ha?1 in 1996. The total above-ground biomass (DM) and its land equivalent ratio (LER) were highest in the 1 : 1 combination ratio. The DM production of intercropped fingermillet was higher in 1996 with higher N than in 1995 with low N application, while those of groundnut were similar in both years. The intercropped groundnut exhibited significantly higher DM production after the fingermillet harvest. The LERs in grain yield were higher in 1996 (1.43 under W and 1.45 under D), than in 1995 (0.87 under W and 1.22 under D). Also, LERs were consistently higher under D than W conditions. Water stress severely reduced the leaf area index (LAI) of fingermillet at a low N, especially in the later stages, whereas higher N alleviated the water stress effect. A close linear relationship was observed between LAI and leaf area (LA) per unit leaf N both for groundnut and fingermillet, with intercrops producing larger LA per unit leaf N than sole crops. Intercropping maintained higher ability in leaf net photosynthesis and transpiration of groundnut up to later stages, and significantly reduced water evaporation from the soil surface under the canopy than sole cropping of fingermillet. These results suggest that three processes associated with the intercropping yield advantages in the groundnut-fingermillet intercrop; 1) higher leaf photosynthesis and vigorous growth of groundnut after the fingermillet harvest, 2) higher LA production per unit N and 3) efficient water use. In conclusion, interspecific shading was considered to be the key mechanism associated with these processes, leading to the intercropping advantages. The degree of the interspecific shade and its effect on growth and yield depended on the available soil N and water. 相似文献
12.
《Field Crops Research》2001,71(3):173-181
While early-maturing crops benefit from intercropping, late-maturing crops usually suffer growth penalties during the intercropping phase. It is possible, however, that recovery or compensation of the late-maturing crops occurs after the harvest of the early-maturing crops. Three field experiments were conducted at Baiyun in 1997 and at Jingtan in 1997 and 1998 to test the hypothesis in wheat/maize and wheat/soybean intercropping. The biomass and nutrient accumulation in intercropped soybean were significantly smaller than in sole soybean before wheat harvest but thereafter increased sharply at Jingtan site in 1997. The rates of dry matter accumulation in the intercropped maize (10.0–20.1 g/m2 per day) were significantly lower than those in the sole maize (17.1–34.8 g/m2 per day) during the early stage from 7 May to 3 August, while mostly intercropped with wheat. After 3 August, however, the rates of intercropped maize, increasing to 58.9–69.9 g/m2 per day, was significantly greater than in sole maize (22.7–51.8 g/m2 per day) at Baiyun site in 1997 and nutrient acquisition showed the same trends as growth. At Jingtan site in 1998, the disadvantage of the border row of intercropped maize resulted from interspecific competition diminished after wheat harvest and disappeared at maize maturity. It was concluded that there was indeed recovery of growth after wheat harvesting in wheat/maize and wheat/soybean intercropping. However, the recovery was limited under N0P0 treatment. The interspecific competition, facilitation and recovery are together contributed to yield advantage of intercropping. 相似文献
13.
为明确宽幅条播对燕麦‖箭筈豌豆间作系统生产力的影响,在常规条播和宽幅条播两种播种方式下设置燕麦单作、箭筈豌豆单作及燕麦‖箭筈豌豆间作三种种植方式,比较分析了不同处理间作物产量、种间关系及燕麦产量构成因素的差异。结果表明,与单作相比,间作燕麦的饲草及籽粒产量显著提高,增幅分别为24.25%~32.77%和27.44%~32.69%,而间作箭筈豌豆的饲草及籽粒产量降低为7.16%~8.08%和2.80%~5.48%。宽幅条播可提高燕麦及箭筈豌豆产量,宽幅条播间作饲草和籽粒产量的土地当量比较常规条播间作分别提高0.03和0.06。在间作中,燕麦的侵占力大于0,实际产量损失大于1,竞争比率大于1,且燕麦的相对拥挤系数大于箭筈豌豆,说明燕麦在间作系统中处于竞争优势。间作燕麦穗数、穗粒数和穗重较单作显著提高,平均增幅分别为24.23%、14.84%和17.43%,其中宽幅条播间作处理的穗粒数、公顷穗数和穗重均显著高于其他处理。由此可见,宽幅条播下通过与箭筈豌豆间作,可提高燕麦生产力和土地资源利用效率。 相似文献
14.
《Field Crops Research》1988,19(1):41-50
The effects of various intercropping arrangements of cassava (Manihot esculenta Crantz) and maize (Zea mays L.) or cowpeas (Vigna unguiculata L. Walp) on crop yields were compared over a 3-year period in Nigeria, in an attempt to improve grain yields of the maize and cowpea intercrops without substantially reducing the cassava root yield. Sole-cropped cassava produced the largest yield; this was significantly reduced by about 40% when intercropped with maize or cowpeas but only when using a 1:2 (cassava:intercrop) row arrangement, mainly because of a reduction in its population density. Cassava yield differences among different row arrangements were more marked when grown with maize than with cowpeas. Maize and cowpea grain yields were reduced by intercropping, but somewhat less so when grown with cassava in widely spaced rows. Cassava row spacing did not affect maize yield, but cowpea yield was affected significantly. Land Equivalent Ratios were always greater than 1, irrespective of the crop combinations and row arrangements. However, increased yields of intercropped cassava:maize were obtained at 1:1 or 2:2 row arrangements and of cassava:cowpea at 2:2 rows, without much reduction in cassava tuber yield. 相似文献
15.
《Field Crops Research》2006,95(2-3):256-267
Intercropping advantages may be influenced by both plant density and relative frequency of the intercrop components. In a field study barley (Hordeum vulgare L.) and pea (Pisum sativum L.) were sole cropped and intercropped at three densities and with two relative frequencies when intercropped.Earlier seedling emergence gave barley an initial growth advantage, assessed using the relative efficiency index (REIc), whereas pea was in general more growth efficient once the initial growth phase had been passed. This reversal in relative growth efficiency along with the observation that early barley dominance did not appear to suppress pea growth indicates that differences in phenology played a role in shaping the prevailing dynamics. Whereas increases in plant density had a positive effect on the growth of pea, the growth of intercropped barley was severely limited by increases in density at the end of the growing period and more so in the pea dominated intercrop. At the final harvest land equivalent ratios (LER) of 0.9–1.2 express resource complementarity in almost all studied intercrops, complementarity that was not directly affected by changes in plant density or relative frequency.Intercropped pea did not increase its reliance on atmospheric nitrogen fixation compared to the pea sole crop. With respect to soil nitrogen uptake there were no effect of plant density but a strong effect of the relative frequency of pea in the intercrop, the greater the proportion the lower the uptake.Changes in the competitive strength of the pea and barley crop over the growing season had a marked effect on the proportion of pea in the final grain yields of the intercrops. At low and recommended density the proportions of pea and barley in the final grain yield was not markedly different from the expected proportions sown; however, at high density the suppression of barley strongly increased the proportion of pea in the final grain yield.Weed infestation levels decreased as density was raised and the suppressing effect of density was clearly stronger the greater the frequency of pea in the crop. Earlier germination and tillering ability of barley are seen as likely explanations of lower weed load in the barley dominated crop treatments.This study points at the potential of employing density and relative crop frequency as “regulators” when specific intercrop objectives such as increased competitiveness towards weeds or specific grain yield composition are wanted. 相似文献
16.
《Field Crops Research》1988,19(3):211-225
Our previous work has shown that early-maturing soybean is suitable for intercropping with vassava at a high latitude (27°S) in south-east Queensland, Australia, as it does not effect the tuber yield. The present study examines whether later-maturing cultivars of soybean with higher yield potential might be more productive. Plant arrangement for cassava was the same in sole crop and in intercrop, while two soybean rows in every six rows were replaced by a row of cassava in intercropping.All soybean cultivars dominated intercropped cassava, and their dry-matter growth and seed yield were not affected by competition with cassava. Growth of cassava was, on the other hand, severely restricted by intercropped soybean, particularly by late-maturing types. After removal of early-maturing soybean, cassava recovered quickly to produce high leaf-area and effectively intercepted solar radiation. Consequential high total dry-matter production, combined with high assimilate allocation to tubers, resulted in tuber yield at the final harvest similar to that in sole cassava. After the removal of late-maturing soybean, however, recovery was poor, and with a short growing season remaining, tuber yields were only 50–60% of that of sole cassava.In addition to their adverse effect on cassave growth, late-maturing cultivars were not suitable as an intercrop because of low harvest indices and low light-conversion efficiency (dry matter produced per unit intercepted radiation), although total light interception during the whole growth of cassava/soybean intercrop was similar to that of sole cassava. The low overall light-conversion efficiency in intercropping with late-maturing cultivars was due to very low dry-matter production of soybean during pod-filling when light interception was still high. 相似文献
17.
Göran Bergkvist Maria Stenberg Johanna Wetterlind Birgitta Båth Sara Elfstrand 《Field Crops Research》2011
Four two-year field trials, arranged in randomised split-plots, were carried out in southern Sweden with the aim of determining whether reduced N fertiliser dose in winter wheat production with spring under-sown clover cover crops, with or without perennial ryegrass in the seed mixture, would increase the clover biomass and hence the benefits of the cover crops in terms of the effect on the wheat crop, on a subsequent barley crop and on the risk of N leaching. Four doses of nitrogen (0, 60, 120 or 180 kg N ha−1) constituted the main plots and six cover crop treatments the sub-plots. The cover crop treatments were red clover (Trifolium pratense L.), white clover (Trifolium repens L.) and perennial ryegrass (Lolium perenne L.) in pure stands and in mixtures. The winter wheat (Triticum aestivum L.) was harvested in August and the cover crops were ploughed under in November. The risk of N leaching was assessed in November by measuring the content of mineral N in the soil profile (0–30, 30–90 cm). In the following year, the residual effects of the cover crops were investigated in spring barley (Hordeum distichon L.) without additional N. Under-sowing of cover crops did not influence wheat yield, while reduced N fertiliser dose decreased yield and increased the clover content of the cover crops. When N was applied, the mixed cover crops were as effective in depleting soil mineral nitrogen as a pure ryegrass cover crop, while pure clover was less efficient. The clover content at wheat harvest as well as the amount of N incorporated with the cover crops had a positive correlation with barley yield. Spring barley in the unfertilised treatments yielded, on average, 1.9–2.4 Mg DM ha−1 more in treatments with clover cover crops than in the treatment without cover crops. However, this positive effect decreased as the N dose to the preceding wheat crop increased, particularly when the clover was mixed with grass. 相似文献
18.
《Field Crops Research》1987,17(1):75-90
The effects of nitrogen fertilization and stubble treatment on soil mineral-N content, moisture status and subsequent crop N uptake were studied in a series of wheat (Triticum aestivum L.) crops planted soon after rice (Oryza sativa L.) harvest. The experiments were part of a programme to define optimum management systems for intensive rice/upland cereal rotations. Stubble management, N application time and rate all influenced amount of soil mineral-N, accounting for up to 52, 67 and 75%, respectively, of the mineral-N variation. In turn, variation in soil mineral-N explained up to 70% of the variation in N accumulation by wheat. N accumulation was highly correlated with crop yield (r2 up to 0.95).Incorporating large quantities of rice stubble at wheat sowing reduced soil NO-3-N concentration by 36% at stem elongation. Both N uptake and yield were reduced by 38% on these plots. Increasing quantities of rice stubble retained on the soil surface increased soil NO3-N concentration by 46%, and wheat on these plots had a 29% increase in N uptake and a 37% increase in yield. Stubble burning rather than retention on the surface resulted in lower soil NO3-N concentration, and this was ascribed to ammonia volatilization resulting from fertilizer contact with ash, and to reduced mineralisation in the drier soil.Application of N at wheat sowing significantly increased mineral-N status at least until stem elongation, while fertilization at tillering or stem elongation significantly increased soil mineral-N content at least until anthesis.It was concluded that stubble and fertilization management techniques can be manipulated in order to regulate soil mineral-N status, which in turn determined plant N uptake. Plant N uptake determined yield. 相似文献
19.
Berseem clover (Trifolium alexandrinum L.) was sown as an intercrop with oats (Avena sativa L.) at 0, 30, 60, 90 and 240 oats plants m?2 in May in 1999 and 2000 in Alberta, Canada. Forage yield and quality were measured at 10‐d intervals between 35 and 88 d after planting (DAP). Yield is defined as the biomass above 6 cm of the soil surface. The dry‐matter (DM) yield of berseem clover in sole crops increased by 5–10 g m?2 d?1 between 35 and 55 DAP and then increased by 21–28 g m?2 d?1 between 55 and 75 DAP. The DM yields of oats sown at 240 plants m?2 increased by 26–28 g m?2 d?1 over the whole period from 35 to 75 DAP. Oats were the dominant component in the intercrops, even at low densities of oats. Berseem clover grown with 60 oats plants m?2 received only 0·24 of the incident light when shading by oats peaked at 65 DAP. DM yields of berseem clover in intercrops with 60 oats plants m?2 averaged 0·14–0·32 of the yields of berseem clover sole crops. Between 35 and 88 DAP in 2000, the crude protein (CP) concentration of berseem clover sole crops declined linearly from 310 to 180 g kg?1 DM, and the CP concentration of oats exhibited a quadratic response, declining from 350 g kg?1 DM at tillering to 110 g kg?1 DM at the soft dough stage. The mean CP concentration of berseem clover in intercrops with 60 oats plants m?2 was 25 g kg?1 less than in berseem clover sole crops, indicating that competition by oats reduced the CP concentration of berseem clover. At later sampling dates, CP and DM yields of intercrops with oats at 60 plants m?2 equalled those with oats at 240 plants m?2. The addition of berseem clover to oats in intercrops at 60 oats plants m?2 reduced the neutral‐detergent fibre concentration by 30 g kg?1 DM compared with oats alone. Oats were very competitive as a companion crop for berseem clover. Adding berseem clover to oats increased forage quality and may provide for increased intake and digestibility of forage to support higher livestock productivity. 相似文献
20.
《Field Crops Research》1998,57(3):309-318
Available soil water is the principal factor that limits the yield potential of wheat (Triticum aestivum L.) and its response to nitrogen (N) under Mediterranean climatic conditions. We examined wheat yield, N fertilizer uptake, and water use for two seasons (1991/1992 and 1992/1993) with total seasonal rainfall of 323 and 275 mm, respectively. In addition to natural rainfall, supplemental irrigation at various rates (1/3, 2/3 and full irrigation) was also considered in assessing these parameters and their interactive effects. Grain yield and dry matter accumulation and N uptake varied between years, mainly due to rainfall and sowing date. Yields were increased by irrigation and N fertilization, with a greater response to N in 1991/1992 and to irrigation in the relatively drier 1992/1993 season. Most fertilizer N was taken up from tillering to anthesis; then it either stabilized or slightly declined, while soil N contributed further to plant N uptake. Compared to rain-fed conditions, more soil and fertilizer N was utilized by the irrigated crop, particularly in 1992/1993. In both years, grain N represented 60% of N accumulated at anthesis under rain-fed conditions, compared to 80% under irrigation. Fertilization and irrigation increased water-use efficiency, particularly under drier conditions. Thus, supplemental irrigation, applied at a sensitive growth stage, would be a valuable management practice for improving yield, water-use efficiency and crop N uptake under the dry conditions of a Mediterranean climate. Given the potential of both irrigation and N to increase output in dry areas, the amounts of both inputs are dictated by rainfall in any one year. 相似文献