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1.
以湖南马尾松毛虫发生地采集的马尾松毛虫为试验材料，选用CPV、Bt 2种微生物复配后对其进行室内药效试验，结果表明：Bt对越冬代松毛虫前12d死亡率的影响显著，死亡率与Bt浓度呈正比，Bt浓度为6×10^7个芽孢／mL时，死亡率可达70．36％；Bt使用浓度为5×10^6芽孢／mL时，第一代松毛虫（群体饲养）处理6d平均死亡率可达70．41％，Bt使用浓度为1×10^7芽孢／mL时，平均死亡率可达75．09％；CPV对越冬代松毛虫处理12d后残留种群带毒率影响显著，带毒率与CPV浓度呈正比，当CPV浓度为2×10^5个多角体／mL时，其带毒率可达53．68％；复配药荆按其对第一代松毛虫（单虫饲养）的药效（前6d死亡率）可分为5类，其平均药效（死亡率）最高达100％，最低的仅为43．12％；CPV-Bt复配药刺防治马尾松毛虫的越冬代和第一代，若只需达到70％杀虫率和50％残留种群带毒率水平，越冬代宜选用2×10^5个多角体／mL＋6×10^7个芽孢／mL，第一代宜选用5×10^4个多角体／mL＋1×10^7个芽孢／mL。 相似文献
2.
南方桉树人工林雨雪冰冻经济损失评估与分析 总被引：1，自引：0，他引：1
针对雨雪冰冻灾害未满5年轮伐期的4类重灾林分开展经济损失评估。结果表明：在萌蘖经营前,不同重灾林分的经营成本与产量均有所差异,只有4年生的重灾林分木材利润为正值,其平均净收入和平均利润分别为16907.20元·hm^-2和2480.85元·hm^-2;其余类型的重灾林分因为经营期较短,木材产量较低不足以完全抵销经营期内的成本。在萌蘖经营中,亦只有4年生重灾林分的收益高于未受灾林分（CK）,其平均净现值（NPV）、内部收益率（IRR）和产出投入比（B/C）分别达18114.00元·hm^-2、57.95%和3.52,比最低分别高98.56%,39.21%和65.79%。不同类型萌蘖经营的NPV和IRR与木材价格和木材产量成正比,而与经营成本和贴现率成反比,IRR不随贴现率的变化而变动。本文还就如何提高灾后桉树人工林的经济效益进行了商讨。 相似文献
3.
苗木生产是一个对水资源依赖度较高的行业,尤其是容器苗木的生产。广州市园林科学研究所长虹苗圃为应对严重缺水对苗木生产的制约,将滴灌·施肥系统引入到容器苗木培育中,取得节水、省肥、提高劳动效率和苗木质量的良好效果。本文在总结广州长虹苗圃五年来应用滴灌·施肥系统实践经验的基础上,分析滴灌·施肥系统在苗木培育中应用的优势与不足,提出应对方法,为推广容器育苗规模化生产中实施节水栽培提供参考。 相似文献
4.
通过在田林县3个不同林龄的马尾松人工林分中设置标准样地并进行每木调查,以D—H曲线进行平均木选择,分径阶伐倒平均木获得生物量数据。以幂指数模型和线性函数为基础对马尾松人工林的单株生物量模型进行了模拟,得到树干、树叶、树皮、树枝、树根和总生物量的回归模型分别为：W=166．0860×（DOH）-2．0497、W=9．1446×（DOH）＋2．1403、W=10．1717×（D^2H）^0.5959、W=0．0035×D^2.9702、W=32．7589×（D^2H）^0.8546、W=258．2048×（D^2H）＋2．0278。数据分析结果表明,马尾松林分平均木生物量随林龄的增加而增大,各器官的生物量所占总生物量的百分比出现明显的变化;各器官的生物量均以树干为最高,并随着林龄的增加而升高;树枝、树叶和树根的比例随着林龄的增加而出现下降。 相似文献
5.
基于中国陆地生态系统通量观测研究网络（ChinaFlux）3年（2005．2007年）的观测数据,研究了千烟洲中亚热带人工林（QYF）和长自山温带混交林（CBF）的气体调节通量动态和气体调节价值累积过程。本文将气体调节服务区分为植被气体调节服务和净生态系统气体调节服务。采用碳税法、造林成本法和工业制氧法对气体调节服务价值化,研究表明气体调节通量具有显著的季节变化。千烟洲人工林和长白山混交林植被的日均CO2吸收量分别为82．00kg·hm^-2·d和59．37kg·hm^-2·d,对应的O2通量分别为59.65kg·hm^-2·d和43．19kg·hm^-2·d。千烟洲人工林和长白山混交林的植被气体调节价值累积过程曲线均为S型,年均植被气体调节服务价值分别为14342．69元·hm^-2和10384．18元·hm^-2。就净生态系统气体调节服务而言,千烟洲人工林全年各月均表现为CO2的净吸收和O2的净释放,而长白山混交林则主要在5-9月表现为CO2的净吸收。千烟洲人工林的净生态系统气体调节价值累积过程曲线为S型,而长白山混交林则为单峰型。千烟洲人工林和长白山混交林的年均净生态系统气体调节服务价值分别为8470．52元·hm^-2和5091．98元·hm^-2。植被气体调节服务和净生态系统气体调节服务主要发生为5-10月。 相似文献
6.
7.
离子注人对光皮桦幼苗保护酶活性及脂质过氧化作用的影响 总被引：1，自引：0，他引：1
采用能量为30Kev／10mA的不同N^＋注入剂量（1、2、3、4、5、6、7、8,9、10×10^16ions·cm^-2）处理光皮桦种子,研究了N^＋离子束注入光皮桦种子后对光皮桦幼苗体内超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）和丙二醛（MDA）含量的影响。结果表明：离子注入剂量在7×10^16ions·cm^-2时,光皮桦幼苗体内保护酶POD、CAT活性达到峰值,MDA含量最低。说明适宜剂量的氮离子注入能激活合成自由基清除酶的能力,在一定程度上削弱种子脂质过氧化作用。 相似文献
8.
9.
林分密度对尾巨桉生物量及生产力的影响 总被引：6，自引：0，他引：6
对湘南低山丘岗区林分密度为600、900和1200株·hm^-2的7年生尾巨桉丰产示范林生物产量进行了测定.结果表明：（1）3种密度林分平均总生物量达到了82.55t·hm^-2,其中乔木层生物量最大,平均为79.22t·hm^-2,凋落物、灌木和草本生物量分别为2.48和0.85t·hm^-2.（2）3种林分密度依低到高其生物量分别为137.33、70.48和39.85t·hm^-2;年均净生产力相当高,分别达到了19.10、9.63和5.23t·hm^-2a-1,高于我国杉木中心产区杉木人工林的水平;不管何种密度的林分,单株、林分及林分各组分的生物量均随密度的增加而明显减小,各组分生物量均存在W干〉W根〉W枝〉W皮〉W叶这样一条规律.（3）树干生物量占总生物量的比例最大,在68.17%以上;林分根系生物量占整个林分生物量比例为9.50%～10.13%,根系集中分布在第1层,随深度的增加而递减.（4）尾巨桉人工林林下有15种灌木植物,7种草本和蕨类植物,其密度较大,除个别绝对优势种特别明显并形成单优种群外,大多数种分布比较均匀.（5）600株·hm^-2的低密度林分结构合理,叶面积指数高,净生物产量也相当高,干材生物量比例高,可作为湘南低山丘岗区短周期纤维材林或矿柱材林或中小径级的民用材林培育的首选密度. 相似文献
10.
不同氮磷钾含量的施肥配比对半年生杨叶肖槿苗木生长及生理的影响 总被引：3，自引：0，他引：3
0,5年生杨叶肖槿盆苗育苗期不同氮、磷、钾含量的施肥配比对其苗木生长及生理影响的试验结果表明：促进其苗高、地茎、叶片数及叶绿素含量4个指标的较优施肥配比为N0．7g·盆^-1、P2O5 0g·盆^-1、K2O0．7g·盆^-1。与对照相比,其苗高提高了1.54倍、地径提高了0．77倍、叶片数增加12．8片、叶绿素含量增加了0．99倍;影响苗木根、茎、叶干重3个指标的较优施肥配比为N0．7g·盆^-1、P2O5 0．7g·盆^-1、K2O0g·盆^-1,其苗木根、茎、叶的干重分别比对照增加了7.00倍、7．66倍、8．54倍;而促进其苗木叶片净光合速率的较优施肥配比为N0．7g·盆^-1、P2O5 0.35g·盆^-1．K2O1．4g·盆^-1,上午10：00时的苗木叶片净光合速率比对照提高2．25μmol／m2·s．在育苗期施肥管理时施用N、P、K3种肥料对杨叶肖槿苗木生长和生理影响的效应不同,以N肥的影响力最大,其次是P,K的影响效应最小。 相似文献
11.
Striga hermonthica is a major constraint to smallholder subsistence agriculture production in the sub-Saharan African region. Low soil fertility
and overall environmental degradation has contributed to the build-up of the parasitic weed infestation. Improved cropping
systems have to be introduced to address the interrelated problems of S. hermonthica and soil fertility decline. Thus, the effects of improved fallow with leguminous shrub Sesbania sesban on maize yields and levels of S. hermonthica infestation on farm land in the bimodal highlands of western Kenya were investigated. The experimental treatments were arranged
in a phased entry, and randomized complete block scheme were six months Sesbania fallow, 18 months Sesbania fallow, six months natural fallow consisting of regrowth of natural vegetation without cultivation, 18 months natural fallow,
continuous maize cropping without fertilizer application, and continuous maize cropping with P and N fertilization. Results
show that Sesbania fallows significantly (p<0.05) increase maize yield relative to continuous unfertilized maize. S. hermonthica plant populations decrease in continuous maize between the first season (mean = 428 000 ± 63 000 ha−1) and second season (mean=51 000 ± 15 000 ha−1), presumably in response to good weed management. S. hermonthica seed populations in the soil decrease throughout the duration of the experiment in the continuous maize treatments. Short-duration
Sesbania fallows can provide modest yield improvements relative to continuous unfertilized maize, but short-duration weedy fallows
are ineffective. Continuous maize cultivation with good weed control may provide more effective S. hermonthica control than fallowing. 相似文献
12.
Improved fallows have been used to reduce time required for soil fertility regeneration after cropping in low input agricultural
systems. In semi-arid areas of Southern Africa, Acacia angustissima and Sesbania sesban are among some of the more widely used improved fallow species. However the residual effects of improved fallows on soil
hydraulic properties during the cropping phase is not known. The aim of this study was to quantify the residual effects of
fallows and tillage imposed at fallow termination on soil hydraulic properties (infiltration rates, hydraulic conductivity
and soil porosity) during the cropping phase. Treatments evaluated were planted fallows of Acacia angustissima, Sesbania sesban and natural fallow (NF) and continuous maize as a control. Steady state infiltration rates were measured using a double ring
infiltrometer and porosity was calculated as the difference between saturated infiltration rates and tension infiltration
measurements on an initially saturated soil. Unsaturated hydraulic conductivity (Ko) and mean pore sizes of water conducting pores were measured using tension infiltrometer at tensions of 5 and 10 cm of water
on an initially dry soil. While there was no significant difference in steady state infiltration rates from double ring infiltrometer
measurements among the fallow treatments, these were significantly higher than the control. The steady state infiltration
rates were 36, 67, 59 and 68 mm h-1 for continuous maize, A. angustissima, S. sesban and NF respectively. Tillage had no significant effect on steady state infiltration rate. Pore density at 5 cm tension was
significantly higher in the three fallows than in maize and varied from 285–443 m−2 in fallows, while in continuous maize the pore density was less than 256 m−2. At 10 cm tension pore density remained significantly higher in fallows and ranged from 4,521–8,911 m−2 compared to 2,689–3,938 m−2 in continuous maize. Unsaturated hydraulic conductivities at 5 cm tension were significantly higher in fallows than in continuous
maize and were 0.9, 0.7, 0.8 cm and 0.5 cm h−1 for A. angustissima, S. sesban, NF and continuous maize, respectively. However there were no significant treatment differences at 10 cm tension. Fallows
improved infiltration rates, hydraulic conductivity and soil porosity relative to continuous maize cropping. Through fallowing
farmers can improve the soils hydraulic properties and porosity, this is important as it affects soil water recharge, and
availability for plant growth 相似文献
13.
Managed short-duration fallows may have the potential to replace longer fallows in regions where population density no longer
permits slow natural fallow successions. The purpose of fallows is not only to improve subsequent crop performance but also
to restore soil fertility and organic matter content for the long term. We therefore evaluated the soil organic matter and
nutrient flows and fractions in a short fallow experiment managed in the western Kenya highlands, and also compared the experimental
area with a 9–12-yr-oldadjacent natural bush fallow. The factorial agroforestry field experiment with four land-use and two
P fertilizer treatments on a Kandiudalfic Eutrudox showed that 31-wk managed fallows with Tithonia diversifolia(Hemsley) A. Gray and Crotalaria grahamiana Wight &Arn. improved soil fertility and organic matter content above those of a natural weed fallow and continuous maize
(Zea mays L.). Post-fallow maize yields were also improved, although cumulative three-season increases in yield were small (0–1.2 Mg
ha−1) when the yield foregone during the fallow season was accounted for. Improvements in yield and soil quality could be traced
to quantity or quality of biomass recycled by the managed fallows. The non-woody recycled biomass produced by the continuous
maize, weed fallow, and tithonia treatments was near 2Mg ha−1, whereas crotalaria produced three times more recyclable biomass and associated N and P. Increases in topsoil N due to the
fallows may have been attributable in part to deep acquisition and recycling of N by the fallows. Particulate macro-organic
matter produced by the fallows contained sufficient N(30–50 kg ha−1) to contribute substantially to maize production. Organic Paccumulation (29 kg ha−1) similarly may play a significant role in crop nutrition upon subsequent mineralization. The effect of the P fertilizer application
on soil properties and maize yield was constant for all land-use systems (i.e., no land-use system × P fertilizer interactions
occurred). There was an indication that tithonia may have stimulated infestation of Striga hermonthica (Del.) Benth., and care must be taken to evaluate the full effects of managed fallows over several seasons.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
14.
Research on improved fallows has concentrated on soil fertility benefits neglecting possible benefits to soil and water conservation.
The effects of improved fallows on rainfall partitioning and associated soil loss were investigated using simulated rainfall
on a kaolinitic soil in Zimbabwe. Simulated rainfall at an intensity of 35 mm h−1 was applied onto plots that were under planted fallows of Acacia angustissima and Sesbania sesban, natural fallow and maize (Zea mays L.) for two years. At the end of 2-years in October 2000, steady state infiltration rates could not be determined in A. angustissima and natural fallow plots, but they were 24 mm h−1 in S. sesban and 5 mm h−1 in continuous maize. The estimated runoff losses after 30 min of rainfall were 44% from continuous maize compared with 22%
from S. sesban and none from A. angustissima and natural fallow plots. Infiltration rate decay coefficients were 36 mm and 10 mm for S. sesban and continuous maize, respectively. In October 2001 after one post-fallow crop, it was still not possible to determine the
steady state infiltration rates in A. angustissima and natural fallows, but they were 8 and 5 mm h−1 for, S. sesban and continuous maize systems, respectively. The runoff loss, averaged across tilled and no-tilled plots, increased to 30%
in the case of S. sesban fallowed plots and 57% for continuous maize; there was still no runoff loss from the other treatments. There were significant
differences (P<0.05) in infiltration rate decay coefficients among treatments. The infiltration rate decay coefficient was 25 mm for S. sesban and it remained unchanged at 10 mm for continuous maize. It is concluded that planted tree fallows increase steady state
infiltration rates and reduce runoff rates, but these effects markedly decrease after the first year of maize cropping in
non-coppicing tree fallows.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
15.
Socioeconomic factors affecting the adoption potential of improved tree fallows in Africa 总被引：2，自引：1，他引：1
S. Franzel 《Agroforestry Systems》1999,47(1-3):305-321
In many parts of Africa, farmers periodically fallow their land, which is allowing land to lie idle for one or more seasons primarily to restore its fertility. This paper assesses the feasibility, profitability, and acceptability of improved tree fallows, which are the deliberate planting of trees or shrubs in rotation with crops to improve soil fertility. Improved tree fallows are assessed at different stages of intensification, drawing on farmers' experiences in three different settings. In extensive systems where land is plentiful and existing fallows with natural regeneration of vegetation restore soil fertility (southern Cameroon), farmers have little incentive to invest labor in establishing improved fallows. Where population density is higher and fallow periods are decreasing and farmers perceive a decline in soil fertility (eastern Zambia), improved fallows have great potential. In intensive systems where land is unavailable and cropping is often continuous (western Kenya), many farmers find it difficult to fallow land. Even here, there is scope for introducing improved fallows, especially among farmers who have off-farm income. Labor constraints and institutional support were found to greatly influence the feasibility of improved fallows. In intensive systems, low returns to cropping, low base yields, and a high opportunity cost of labor increase the returns to improved fallows. Principal factors associated with acceptability include past perception of soil fertility problems, past use of measures for improving soil fertility, current fallowing, economic importance of annual cropping, and wealth level. Adoption potential may be increased by reducing fallow periods, intercropping trees and crops during the first season, reducing establishment costs, producing higher value by-products, and by encouraging farmers to test improved fallows on high-value crops.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
16.
Short-term improved fallow technology, which is characterised by deliberate planting of fast growing N2 fixing legumes species in rotation with crops is currently being promoted for soil fertility replenishment in the small holder farms in the tropics. Recent research and extension efforts on this technology have mainly focused on a narrow range of species. There is a need to evaluate more alternative species in order to diversify the options available to farmers and hence reduce the risks of over dependence on fewer species. We evaluated twenty-two shrubby and herbaceous species for their site adaptability, biomass and nutrient accumulation, biomass quality and maize yield response to soil incorporated plant biomass after the fallow (six and twelve months) in three different field experiments on a Kandiudalfic Eutrudox in western Kenya. Species which yielded large amounts ofthe most biomass N adequate for two to three maize crops were Sesbania sesban, Tephrosia vogelii, Tephrosia candida, Crotalaria grahamiana, Dodonea viscosa, Colopogonium mucunoides, Desmondium uncinatum, Glycine wightii and Macroptilium atropurpureum. Most fallow species tested recycled <22 kg P ha–1 in plant biomass. Significant amounts of K were recycled through plant biomass of Sesbania sesban, Tithonia diversifolia, Tephrosia candida, Crotalaria grahamiana, Dodonea viscosa, Colopogonium mucunoides, Desmondium uncinatum, Glycine wightii, Macroptilium atropurpureum and natural weed fallows. Recyclable K in plant biomass ranged between 4 and 188 kg ha–1Two methods of establishing S. sesban and T. vogelii fallows did not result in significant differences in biomass and nutrient yields at the end of the fallow period. Shrubby species gave Hhigh lignin (>10%) and polyphenol (>2%) concentrations. were found only in the shrubby species, and the (Ppolyphenol + lignin ): N ratio varied widely (0.3–5) amongst the species. evaluated. Maize yield increased by two-fold in the first season following the fallow phase compared with continuous maize for most species. Results suggest that there are a wide variety of legumes that could be used for use in improved fallow technologies aimed at ameliorating nutrient degraded soils and subsequently enhancing crop yields.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
17.
In eastern Zambia, nitrogen deficiency is a major limiting factor for increased food production. Soil fertility has been declining because of nearly continuous maize (Zea mays) cultivation with little or no nutrient inputs. The use of short-duration tree fallows was one of several agroforestry options hypothesized to restore soil fertility. Sesbania sesban, an indigenous N2-fixing tree was the most promising among species tested in screening trials. Several studies since 1987 have demonstrated the dramatic potential of two- or three-year sesbania fallows in restoring soil fertility and increasing maize yields. Analyses showed that these improved fallow systems were feasible, profitable, and acceptable to farmers. Results suggest that high maize yields following fallows are primarily due to improved N input and availability by the fallows. The potential to increase maize production without applying mineral fertilizers has excited thousands of farmers who are enthusiastically participating in the evaluation of this technology. The number of farmers who are testing a range of improved fallow practices has increased from 200 in 1994 to over 3000 in 1997. Presently, a strong network of institutions comprising government, NGOs, development projects, and farmer organizations is facilitating the adaptive research and expansion of improved fallow technology in eastern Zambia. Key elements in the research process that contributed to the achievements are effective diagnosis of farmers' problems, building on farmers' indigenous knowledge, generating several different fallow options for farmers to test, ex-ante economic analysis, farmer participation in on-farm trials, and development of a network for adaptive research and dissemination.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
18.
Nitrogen deficiency is widespread in southern Africa, but inorganic fertilizers are often unaffordable for smallholder farmers. Short-duration leguminous fallows are one possible means of soil fertility restoration. We monitored preseason topsoil (0 to 20 cm) ammonium and nitrate, fallow biomass production and grain yields for three years in a relay cropping trial with sesbania [Sesbania sesban (L.) Merr.] and maize (Zea mays L.). Sesbania seedlings were interplanted with maize during maize sowing at 0, 7400 or 14,800 trees ha–1, in factorial combination with inorganic N fertilizer at 0 or 48 kg N ha–1 (half the recommended rate). After maize harvest, fallows were allowed to grow during the seven-month dry season, and were cleared before sowing the next maize crop. Both sesbania fallows and inorganic N fertilizer resulted in significantly greater (P < 0.01 to 0.05) preseason topsoil nitrate-N than following unfertilized sole maize. In plots receiving no fertilizer N, preseason topsoil inorganic N correlated with maize yield over all three seasons (r
2 = 0.62, P < 0.001). Sesbania fallows gave significantly higher maize yields than unfertilized sole maize in two of three years (P < 0.01 to 0.05). Sesbania biomass yields were extremely variable, were not significantly related to sesbania planting density, and were inconsistently related to soil N fractions and maize yields. Short-duration fallows may offer modest yield increases under conditions where longer duration fallows are not possible. This gain must be considered against the loss of pigeonpea (Cajanus cajan L. Millsp) harvest in the similarly structured maize-pigeonpea intercrop common in the region.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
19.
Improved fallow is a technology that can help to raise agricultural productivity in systems of poor soil fertility and low
financial capital. Models, once calibrated, can be used to investigate a range of improved fallow systems relatively quickly
and at relatively low cost, helping to direct experimental research towards promising areas of interest. Six fallow crop rotations
were simulated using the WaNuLCAS model in a bimodal rainfall setting in Kenya over a 10 year period: (A) alternating fallow
and crop seasons, (B) one season fallow followed by three seasons crop, (C) one season fallow followed by four seasons crop,
(D–F) 1–3 seasons fallow periods followed by 3–5 seasons crop. The strategies were tested using a number of fallow growth
rates, soil clay contents, and rainfall amounts to determine the interaction of fallow rotation and biophysical variables
on maize (Zea mays (L.)) yield and sustainability (organic matter, N2 fixation, leaching). The best simulated fallow strategies doubled maize yield compared to continuous maize over a 10 year
period. Across all biophysical treatments strategy A and B of no more than three consecutive cropping seasons and of one consecutive
fallow season yielded the most maize. This was because fallow benefits were largely due to the immediate fallow soil fertility
benefit (IFB) rather than the cumulative benefit (CFB). The difference in yield between the two strategies was through a balance
between (1) their interaction with the biophysical variables affecting accumulation of organic matter, hence increasing soil
fertility and (2) the extra intrinsic soil fertility used for maize productivity by the inclusion of more cropping seasons
within the rotation. We propose the following conceptual framework to manage fallows for maximum maize yield: when environmental
factors are strongly limiting to fallow and crop growth then fallow strategy A would be the best strategy to employ (less
risk but more labour) and when factors are less limiting then strategy B would be the best to employ. 相似文献
20.
Sesbania [Sesbania sesban (L.) Merr.] fallows are being promoted as a means for replenishing soil fertility in N-depleted soils of small-scale, resource-poor
farmers in southern Africa. Knowledge of soil water distribution in the soil profile and water balance under proposed systems
is important for knowing the long-term implications of the systems at plot, field and watershed levels. Soil water balance
was quantified for maize (Zea mays L.) following 2-year sesbania fallow and in continuous maize with and without fertilizer during 1998–1999 and 1999–2000 at
Chipata in eastern Zambia. Sesbania fallow increased grain yield and dry matter production of subsequent maize per unit amount
of water used. Average maize grain yields following sesbania fallow, and in continuous maize with and without fertilizer were
3, 6 and 1 Mg ha−1 with corresponding water use efficiencies of 4.3, 8.8 and 1.7 kg mm−1 ha−1, respectively. Sesbania fallow increased the soil-water storage in the soil profile and drainage below the maximum crop root
zone compared with the conventionally tilled non-fertilized maize. However, sesbania fallow did not significantly affect the
seasonal crop water use, mainly because rainfall during both the years of the study was above the normal seasonal water requirements
of maize (400 to 600 mm). Besides improving grain yields of maize in rotation, sesbania fallows have the potential to recharge
the subsoil water through increased subsurface drainage and increase nitrate leaching below the crop root zone in excess rainfall
seasons.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献