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61.
对20个杉木不同家系的苗木进行磷素营养要求试验,1年生苗木盆栽试验结果表明:杉木不同家系苗木对磷素营养反应敏感,2g磷处理使苗高、地径分别增益3.7%—96.5%、7.4%—61.1%,4g磷处理使苗高、地径分别增益2.1%—83.1%、3.7%—57.9%,杉木苗期需要磷素营养。三明38、三明67、三明48、三明58四个家系生长比较理想,在0g磷处理下,1年生平均苗高13.0—15.99cm,平均地径0.23—0.27cm,这4个家系具有更大的生长潜力,20个家系间对磷素营养要求方面不存在显著的差异。 相似文献
62.
H. W. Fassbender L. Alpízar J. Heuveldop H. Fölster G. Enríquez 《Agroforestry Systems》1988,6(1):49-62
Models for cycles for organic matter and nutrients element (N, P, K, Ca and Mg) are presented for the agroforestry systems of cacao (Theobroma cacao) withCordia alliodora orErythrina poeppigiana in Turrialba, Costa Rica.For the models, system reserves (soil, humus, vegetation divided into leaves, branches, stems, fine roots, fruits) and transference between compartments (production and decomposition of litter residues) inputs (fertilizer, rainfall) and outputs (harvests) of the system are considered.The implications of the models are discussed in detail.Aspects of net primary production in the systems studied are considered.N fixation is calculated on the basis of balances. Analysis of soil water showed high variations that coincided with rainfall patterns and pruning of theE. poeppigiana.For part I see Vol. 4, No. 3, 1986 For part II see this issueAgroforestry Project, CATIE/GTZ (Tropical Agricultural Research and Training Center/Gesellschaft für Technische Zusammenarbeit), Turrialba, Costa Rica 相似文献
63.
64.
Xiaoming Zhang Xinxiao Yu Sihong Wu Tianxing Wei Xuepei Zhang 《Frontiers of Forestry in China》2006,1(3):336-342
According to fixed-position data for 1985–2003 from nine runoff plots of Caijiachuan watershed which lies in Jixian County
of Shanxi Province in Loess area, this paper studied the relationship between vegetation and runoff and sediment production
in sloping lands in detail, which helps to provide scientific basis for vegetation re-construction and studies on environmental
transformation of water and sediment in watersheds of Loess area. Although, many study results testify that forest vegetation
has an important function in soil and water conservation and cutting runoff, the effect of vegetation on runoff and sediment
transmission is complicated, and this needs to be studied in depth. The results of the paper showed the following. Firstly,
the natural secondary forest performs better function of soil and water conservation than artificial Robinia pseudoacacia forest, and runoff and sediment produced in the former in individual rainfall were 65%–82% and 23%–92% of those produced
in the latter. At the same time, better correlative relationship between runoff and sediment production and rainfall and rainfall
intensity were testified by multiple regression, but the correlation decreased gradually with the increase of canopy density
of forest. Secondly, the difference of runoff and sediment production in several land use types was very distinct, and the
amount of runoff and sediment produced from Ostryopsis davidiana forest and natural secondary forest were the least, and runoff and sediment produced from in artificial Robinia pseudoacacia forest and Pinus tabulaeformis forest were 5-fold as much as those from O. davidiana forest. Besides, runoff and sediment produced in mixed planting of apple trees and crops were 16.14-fold and 2.96-fold than
those of O. davidiana forest, respectively, but the amount decreased obviously after high-standard soil preparation in the case of the former.
Thirdly, based on gray cognate analyses of factors affecting runoff and sediment production in sloping land, the factors of
stand canopy density and herb and litter biomass were the most significant ones, whose gray incidence degree exceeded 0.6.
Therefore, mixed forest with multi-layer stand structure and shrub forest should be developed in vegetation re-construction
of Loess area, which will help to increase coverage and litter thickness in order to cut down the runoff and sediment dramatically
in sloping land.
__________
Translated from Chinese Journal of Applied Ecology, 2005, 16(9): 1,613–1,617 [译自: 应用生态学报, 2005, 16(9): 1,613–1,617] 相似文献
65.
J. Heuveldop H. W. Fassbender L. Alpízar G. Enríquez H. Fölster 《Agroforestry Systems》1988,6(1-3):37-48
During 7 years (1979–1985) cacao harvests (beans and husks) have been recorded for the agroforestry systems ofTheobroma cacao underCordia alliodora andErythrina poeppigiana shade trees. The mean oven dry cacao yields were 626 and 712 kg.ha−1.a−1 cocoa beans underC. alliodora andE. poeppigiana respectively. Harvests have gradually increased over the years and the plantation has now reached maturity.
Annual extraction of N, P, K, Ca and Mg in fruits, which is relatively small, was calculated on the basis of chemical analyses.
The following average values were found (kg.ha−1.a−1):
At the age of 8 years, theC. alliodora trees have reached 26.7 cm diameter (DBH) and 14.0 m in height. Mean annual growth (from age 5 to 7) is 14.6 m3.ha−1.a−1.
Natural plant residue production has been measured for 4 years (Nov. 1981–Oct. 1985). UnderE. poeppigiana it has reached a value of 8.91 t.ha−1.a−1 and underC. alliodora 7.07 t.ha−1.a−1. The shade trees have contributed 57 and 47% respectively. Transference and decomposition rates are high and important in
the nutrient cycles.
The nutrient content of the litter was analysed and corresponding average yearly transfers were (kg.ha−1.a−1):
For part I see Vol. 4, No. 3, 1986.
Agroforestry Project, CATIE/GTZ (Tropical Agricultural Research and Training Center/Gesselschaft für Technische Zusammenarbeit),
Turrialba, Costa Rica 相似文献
66.
宁夏引黄灌区灌淤土壤磷累积状况及磷肥肥效研究 总被引:1,自引:0,他引:1
宁夏第二次土壤普查结果表明,灌淤耕地速效磷含量明显提高,平均含量由1985年的16.3 mg/kg增加到现在28.04 mg/kg.吴忠市利通区东塔乡国家农业科技示范园区磷肥肥效试验研究表明:土壤速效磷含量在50~60 mg/kg高水平下,小麦套玉米施磷效果较低,小麦玉米总产量肥料函数效应达显著水平.施P2O5最大量1... 相似文献
67.
施磷量对旱地小麦氮磷钾和干物质积累及产量的影响 总被引:10,自引:0,他引:10
针对目前农业生产中存在的施肥增产效应下降问题,研究了磷肥用量对冬小麦养分、氮磷钾和干物质积累及产量的影响,以期为高产高效施肥提供依据.在黄土高原旱地进行田间试验,设不施磷,施磷P2O5 50kg/hm2(不足)、P2O5 100 kg/hm2(适量)和P2O5 150 kg/hm2(高量)4个水平,在不同生长期采样测定... 相似文献
68.
陕北不同土地利用类型下土壤无机磷形态分布及有效性研究 总被引:2,自引:0,他引:2
采用蒋柏藩-顾益初无机磷分级方法,对黄土高原两种农田土壤剖面(0~100 cm)中无机磷形态分布特征进行了研究.结果表明:两种农田土壤剖面(0~100 cm)中无机磷形态占全磷的90.95%;无机磷又以Ca-P为主,所占比例在87.86%~92.55%之间;糜子地土壤剖面中无机磷总量、Ca2-P、Ca8-P、Al-P和... 相似文献
69.
Getaneh K. Ayele Azalu A. Gessess Meseret B. Addisie Seifu A. Tilahun Tigist Y. Tebebu Daregot B. Tenessa Eddy J. Langendoen Charles F. Nicholson Tammo S. Steenhuis 《Land Degradation \u0026amp; Development》2016,27(2):270-280
Gully erosion reduces agricultural productivity by destroying valuable land resources, increases sediment concentrations, reduces water quality, and fills up reservoirs. Gully rehabilitation has proven to be challenging especially in the high‐rainfall areas of the Ethiopian Highlands and has therefore had limited success. This paper describes a successful low‐cost gully rehabilitation effort with community participation in the Birr watershed in the Blue Nile basin that begun in early 2013. Initially, farmers were reluctant to participate for religious reasons, but with the aid of local priests and respected elders, community discussions, and a visit to a rehabilitated gully, a consensus was reached to rehabilitate a 0·71‐ha upland gully. The rehabilitation measures consisted of regrading the gully head at a 45° slope, constructing low‐cost check dams from locally available materials, and planting Pennisetum purpureum grass and Sesbania sesban. At the end of the first post‐implementation rainy season, 2,200 tons of soil was conserved by the constructed check dams and newly planted vegetation, compared with soil losses of 680 and 560 tons in two untreated, nearby gullies. In 2014, an additional 3,100 tons of soil was conserved. In 2013, the marginal rate of return (MRR) on the gully rehabilitation investment was 2·6 based on the value of increased forage production alone. When we include trapped soil nutrient values, the rehabilitation MRR was increased to 10. Although these numbers are impressive, the best proof of the success was that farmers on their own initiative rehabilitated an additional five gullies in 2014. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
70.
Amrakh I. Mamedov Benayahu Bar‐Yosef Irit Levkovich Rivka Rosenberg Avner Silber Pinchas Fine Guy J. Levy 《Land Degradation \u0026amp; Development》2016,27(6):1629-1639
Application of organic wastes to cultivated lands can replace mineral fertilizers but may also alter soil physical properties and enhance pollution potential. The objective of this study was to investigate the effects of biosolids [composted manure (MC) and activated sludge (AS)] and specific biosolid component [orthophosphate (OP), phytic acid (PA) and humic acid (HA)] application on soils differing in texture [loamy‐sand (Ramat‐HaKovesh, RH), loam (Gilat, GL) and clay (Bet‐Dagan, BD)], infiltration rate, runoff volume and soil sediment loss. The soils were packed in erosion boxes (400 × 200 × 40 mm) and subjected to six consecutive simulated rainstorms, each of 186 mm deionized water. The results showed that runoff volume and sediment loss from untreated soils increased with increasing clay contents. In treated soils, the response to AS application differed from the response to other amendments; in the BD clay and GL loam, it was the only amendment that caused a decrease in sediment removed by runoff. In the RH loamy‐sand, all amendments reduced the final infiltration rate, but only AS and HA increased the measured runoff. It is proposed that the difference in the response of the soils to the amendments is associated with the soil's ability to attenuate changes in the negative charge on the clay edges following the increase in the specific adsorption of charged anions, thus controlling clay swelling and maintaining aggregate integrity. The effects of amending soils with a source of organic matter in order to control runoff and soil erosion are not straight forward and depend on soil and amendment properties. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献