果园生草的生态效应及在果树上的应用

从生草对果园土壤、果园微域环境、果树生长的影响综述了国内外近年来研究的新进展.结果表明:和传统的果园土壤清耕模式相比较,果园生草具有明显的水土保持作用,增加土壤全N、速效P及交换K含量,显著增加土壤有机质含量,改善土壤结构,改善土壤酶活性,使果园微域环境温度变化趋于平缓,果园天敌种类和数量增加,有利于害虫的生物防治,增加果实含糖量,改善果实着色;同时,生草降低果园土壤水分含量,降低果树加粗生长,减少果实产量,有利于病虫滋生.展望了果园生草在我国现阶段无公害果品生产、果园循环经济中的广阔应用前景.指出了我国推广果园生草需要注意及应当进一步研究的问题.     

带幅设计对玉米/苜蓿间作群体光环境特征及光能利用效率的影响北大核心CSCD

探究间作带幅设计对玉米/苜蓿间作群体光环境特征、产量及光能利用效率(LUE)的影响,提出黄土高原旱作条件下玉米/苜蓿间作群体最佳带幅比例。研究设置了玉米单作(SM)、紫花苜蓿单作(SA)以及玉米/紫花苜蓿1∶2(I_(12))、2∶2(I_(22))和2∶4(I_(24))间作5种种植模式,并采用田间试验和数学模拟相结合的方法,分别测定了玉米和苜蓿的干物质产量及作物冠层光合有效辐射(PAR)等指标;建立了考虑光线入射角度和群体冠层结构几何关系的玉米/苜蓿间作群体辐射传输模型,并用实测值对其进行了验证。试验结果表明,在2018年,单作处理的苜蓿干物质产量显著高于间作处理(P<0.05),而在2019年各间作处理苜蓿的干物质分别比单作高197.8、180.3和197.0 g·m^(-2);处理I_(12)、I_(22)和I_(24)两年总的玉米生物量比SM处理高12.1%、0.9%和23.9%。所有间作处理的土地当量比在2019年均大于1.0,表现出间作优势。辐射传输模型可准确模拟玉米/苜蓿间作群体冠层底部的光合有效辐射,间作群体光合有效辐射模拟值与实测值的平均绝对误差和均方根误差分别为59.0和66.6μmol·m^(-2)·s^(-1)。除玉米和苜蓿生育前期及玉米收获后,不同间作处理苜蓿群体冠层上方的PAR均低于单作苜蓿。2018和2019年I_(12)、I_(22)和I_(24)间作处理玉米的光能利用效率分别比单作处理高52.5%、9.3%、51.7%和28.5%、9.6%、21.0%,而间作苜蓿的LUE仅在2019年显著高于单作19.2%、32.4%和20.9%(P<0.05)。因此,合理的玉米/苜蓿间作带幅搭配可改善苜蓿的光照环境,提高其光能利用效率,尤其是玉米/紫花苜蓿2∶4间作群体光能利用效率和产量优势显著,建议在具有类似气候的地区推广种植。     

不同造林密度杨树速生丰产林成熟龄的研究

在不同密度欧美类杨速生丰产林生长规律的基础上,应用净现值方法对不同密度林分的经济成熟进行了分析。依据利润最大化的原则,确定不同密度林分的成熟龄;数量成熟龄和经济成熟龄随密度的增大而减小,林分经济成熟龄的时间是7~9 a(P=5.22%),数量成熟龄是12~14 a;对比其他密度,330株/hm2林分更适宜培育大径材;另外,对间作条件下的杨树速生丰产林的经济成熟龄与经济效益进行了分析。     

黄藤栽培技术的研究*

论述了黄藤的壮苗培育和造林技术、藤林的经营采收技术及经营黄藤林经济效益。２３°３０’Ｎ以南为黄藤适生栽培区，年均温２０～２４．５℃，极端低温大于一２．８℃，１５Ｃ活动积温大于５８００℃；年降雨量大于１２００ｍｍ。适宜的立地：林内相对光照强度大于５０％，土壤润湿，表土有机质含量大于２％，全氮大于０．１％，全磷大于０．０１％，ｐＨ４．４～６．７。在１５℃条件下，保持种子在２９％的安全含水率的湿藏法，能有效保持种子活力６个月。黄藤造林的综合技术质量指标：１年生苗木的合格苗叶片数大于４．Ｏ片，苗高大于２５ｃｍ，壮苗叶片数大于５．Ｏ片，苗高大于３５ｃｍ；８年生藤林成丛株数大于１３．Ｏ株，１２年生藤林原藤产量７０００ｋｇ／ｈｍ２，速生丰产林平均成丛株数大于５０株，总茎长大于１００ｍ／丛，采收量大于１００００ｋｇ／ｈｍ２。本文还论述了黄藤的工艺成熟龄、采收间隔期、采收和经营方法以及经营黄藤林的经济效益。     

Intercropping field crops between rows of Leucaena leucocephala under rainfed conditions in northern India

A field study was conducted for six years (1981–1986) on sandy loam soil on intercropping hedgerows of Leucaena leucocephala (Lam) de Wit. with three field crops viz. maize (Zea mays L), black gram (Vigna mungo L) and cluster bean (Cyamopsis tetragonoloba L Taub.). In treatments 1 and 2 Leucaena hedges were planted as pure crops at close (25 cm × 75 cm) and wide (25 cm × 375 cm) spacings. In treatments 3, 4 and 5 the three field crops were intercropped between the hedgerows of Leucaena at the wide spacing, and in treatments 6, 7 and 8 the field crops were raised as pure crops. Leucaena was topped to 75 cm each time it attained a height of 175 cm. The pure crop of Leucaena at close spacing produced an average, over the six years, of 34 t ha⁻¹a⁻¹ of green fodder and 9.4 t ha⁻¹a⁻¹ of air dry fuelwood. The Leucaena at wide spacing produced 18.9 t ha⁻¹a⁻¹ of green fodder and 6.3 t ha⁻¹a⁻¹ of fuelwood. Intercropping with field crops decreased the yield of green fodder and fuelwood. The yield of all the field crops was less when raised as intercrops than as pure crops. Mean maximum net returns were obtained from intercrops of Leucaena and cluster bean (Rs 3540 ha⁻¹a⁻¹) which were significantly higher than the returns from pure crop of Leucaena at wide spacing but similar to the returns from pure crops of cluster bean. Leucaena with maize (Rs 3273 ha⁻¹a⁻¹) and black gram (Rs 3125 ha⁻¹a⁻¹) gave significantly higher net returns over pure crops of Leucaena at wide spacing, maize and black gram. ICRISAT = International Crops Research Institute for the Semi-Arid Tropics- Hyderabad, India. CIAT = Centro International de Agricultura Tropical - Cali - Columbia     

林豆复合生态系统土壤理化性质的研究

本文对混种大豆的落叶松.大豆、水曲柳-大豆复合生态系统土壤理化性质进行研究。结果表明,在一个生长季内混种后的土壤物理性质得到了改善。落叶松.大豆与水曲柳一大豆复合生态系统的土壤容重为1.112g/cm3和1.058g/cm3均低于相对应的纯林:混种大豆后土壤总孔隙度增加。两种林-豆复合生态系统土壤有机质分别比对应纯林高1.77倍和1.09倍:落叶松一大豆复合生态系统全氮和水解氮含量分别高于落叶松纯林4.2%和53.0/%,水曲柳-大豆复合生态系统全氮和水解氮含量分别高于水曲柳纯林75.5%和3.3%:混种大豆后全磷含量降低,而有效磷含量则增加:落叶松-大豆复合生态系统全钾和有效钾比落叶松纯林高0.6%和17.5%,水曲柳-大豆复合生态系统全钾和有效钾分别比水曲柳纯林高56.4%和21.8%。图1表3参27。     

The potential of intercropping as an alternative land use system in temperate North America

The success of many intercropping systems in North America is attributable to the generation of a short term return from an agricultural crop during the early, unprofitable years of a longer term crop that is fruit, nuts or wood. This highly-efficient use of land and related profitability are important not only in the development of intercropping systems per se, but also in other applications which have tremendous potential independent of profitability. For example, intercropping can be effectively used during the establishment phases of hardwood plantations where it is essential to have a high level of weed control, the costs of which are often recovered with the agricultural production. Intercropping can also be used to grow trees rapidly and with a form that can be easily integrated into recreational or park situations, or urban fringe areas. In an urban context, intercropping can be used to grow trees in agricultural areas that are likely to be developed where traditional forestry options are not appropriate and the value of younger, thrifty trees may enhance property values far in excess of the cash value of the wood.     

Rural livelihood benefits from participation in the taungya agroforestry system in Ondo State of Nigeria

This study examines the strategies and benefits of the taungya farming system to both the government and the rural economy in Nigeria. An interview survey was conducted in which data were collected from 115 randomly selected farmers in five villages in the Oluwa forest reserve, Ondo State, Nigeria. The study examines the extent of participation of rural dwellers in plantation development through taungya farming and the degree of success of this system as an afforestation method. The farmers were predominantly illiterate, within the age bracket of 35–54 years and with small farm holdings. Twenty nine percent relied totally on food from the forest reserve for their livelihood, while 71% also had farm holdings in free areas. Land within the reserve is allocated to farmers free of charge but compensation is paid to landlords on land from free areas. A statistically significant difference was detected in income from the two sources of farmland for the households and but not in the size of land allocated under taungya and free areas. About 184 farmers are involved in taungya annually, and 410 ha of Tectonia grandis has been established for the government of Ondo State.     

An agroforestry practice for the development of salt lands usingProsopis juliflora andLeptochloa fusca

High salt concentration in the soil is a serious problem in vast areas of otherwise productive agricultural lands in India. Establishment of salt tolerant vegetation could be an effective way of ameliorating this problem. In an 8-year field trial on an alkali soil, growth and biomass production ofProsopis juliflora was greater in sole stand than when interplanted with the grassLeptochloa fusca, but soil improvement was greater for the mixed tree-grass treatment.Prosopis accumulated substantially more biomass nutrients when in sole stand, but total nutrient recycling was similar with and without grass. Less salt tolerant but more palatable fodder crops such asTrifolium resupinatum, T. alexandrium andMelilotus denticulata were successfully grown withProsopis after removingL. fusca in theProsopis plus grass treatment 50 months after commencement. Tentative economic analysis suggests theProsopis plus grass system gives higher returns. TheProsopis-Leptochloa system combines production with biological reclamation, and is an appropriate form of reclamation agroforestry for alkali lands.     

Technical efficiency in the spice based agroforestry sector in Matale district, Sri Lanka

Spices constitute an important sub-sector of the economy of Sri Lanka. Most perennial spices are cultivated in agroforestry types of farming systems. A field survey was conducted covering 127 agroforestry farmers in six divisional secretariats in Matale district during the period of October to December 2002. Technical efficiency of spice based agroforestry systems was estimated in order to identify the potential increase in production without incurring additional costs for farm inputs. The factors affecting technical efficiency and constraints and potential of the agroforestry system were also investigated. According to a stochastic frontier production function using a Cobb–Douglas model, hired labour, organic fertilizer, inorganic fertilizer, land size, and soil conservation measures showed significant positive effects on the agroforestry production. The mean technical efficiency of the spice based agroforestry systems was 84.32%. According to the inefficiency model the efficiency increased significantly as a result of farm visits by extension officers, participation in farmer training, less sloping lands, more experience, and higher diversity of the agroforestry system. Technical efficiency decreased, however, with higher education level of the farmer and with higher off-farm income. Unsustainability of the agroforestry system is seen as a result of a␣range of constraints related to productivity, market, technology and institutions.