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1.
Integration of shrubs into the smallholder crop-rangeland-livestock farming systems in non-tropical dry areas could reduce feed gaps, rangeland degradation and desertification, but data on yield and fodder quality of most native and exotic shrubs are scanty. The study aimed at identifying shrubs for dryland agroforestry based on agronomic and fodder quality attributes. Fodder and wood yield, percent fodder (FBR) and fodder quality of 26 non-legume shrubs were determined from 6 to 8 months regrowth in north-west Syria. Seed yield was estimated from plants that were not cut. Fodder (31–87 Mg DM ha−1), wood (16-2064 Mg DM ha−1) and seed (0-132 Mg DM ha−1) yield, FBR (24–87%), fodder concentrations of crude protein (69–195 g kg−1.), acid detergent lignin (ADL) (24–109 g kg−1), acid detergent fiber (ADF) (102–267 g kg−1), neutral detergent fiber (NDF) (214–526 g kg−1), in vitro organic matter digestibility (IVOMD) (391–526 g kg−1), and in vitro gas production after 24 h of incubation (25–39 ml 200 mg−1 DM) varied (P < 0.05) among the shrubs. Atriplex halimus-halimus and A. herba-alba from Spain, A. canescens, A. ploycarpa and A. lentiformis from USA, A. halimus and A. herba-alba from Syria and A. nummularia from Australia and South Africa had greater potential for development of dryland agroforestry technologies. The promising shrubs could be integrated into the rangeland-crop-livestock systems in non-tropical dryland environs to provide fodder, fuel-wood, shade, medicine, stabilize sand-dunes, and sequester carbon; thereby contributing to mitigation of rangeland degradation and global warming; if major constraints to adoption of fodder trees such as agronomic problems, low multipurpose value, land shortage and quality seed supply could be overcome.  相似文献   

2.
The effect of pruning all branches (complete pruning) or retaining one branch (partial pruning) on the dynamics of nitrogen cycling in aboveground biomass, nitrogen supplying power of an amended Eutric Cambisol, and fine root length, was studied in an Erythrina poeppigiana (Walp.) O.F. Cook—tomato (Lycopersicon esculentum Mill.) alley cropping practice in Turrialba, Costa Rica during 1999–2000. Over the 1 year pruning cycle, in which trees were completely or partially pruned four times, respective aboveground biomass production was 4.4 Mg or 7 Mg ha−1 (2-year-old trees) and 5.5 Mg or 9 Mg ha−1 (8-year-old trees); N cycled in aboveground biomass was 123 kg or 187 kg ha−1 (2-year-old trees) and 160 kg or 256 kg N ha−1 (8-year-old trees); mean fine root length was 489 or 821 m (2-year-old-trees), 184 or 364 m per tree (8-year-old-trees). Pruning intensity did not significantly affect net N mineralisation and net nitrification rates during the tomato-cropping season. For the tomato crop, pre-plant mean net N mineralisation rate of 2.5 mg N kg−1 soil day−1 was significantly lower than 16.7 or 11.6 mg N kg−1 soil day−1 at the end of vegetative development and flowering, respectively. Mean net nitrification rates of 3.5, and 4.3 mg N kg−1 soil day−1, at pre-plant and end of vegetative development, respectively, were significantly higher than 0.3 mg N kg−1 soil day−1 at end of flowering. In humid tropical low-input agroforestry practices that depend on organic inputs from trees for crop nutrition, retention of a branch on the pruned tree stump appears to be a good alternative to removal of all branches for reducing N losses through higher N cycling in aboveground biomass, and for conserving fine root length for higher N uptake, although it might enhance competition for associated crops.  相似文献   

3.
The above-ground biomass and production, below-ground biomass, nutrient (NPK) accumulation, fine roots and foliar characteristics of a 8-year-old silver birch (Betula pendula) natural stand, growing on abandoned agricultural land in Estonia, were investigated. Total above-ground biomass and current annual production after eight growing seasons was 31.2 and 11.9 t DM ha−1, respectively. The production of stems accounted for 62.4% and below-ground biomass accounted for 19.2% of the total biomass of the stand. Carbon sequestration in tree biomass reaches roughly 17.5 t C ha−1 during the first 8 years. The biomass of the fine roots (d < 2 mm) was 1.7 ± 0.2 t DM ha−1 and 76.2% of it was located in the 20 cm topsoil layer. The leaf area index (LAI) of the birch stand was estimated as 3.7 m2 m−2 and specific leaf area (SLA) 15.0 ± 0.1 m2 kg−1. The impact of the crown layer on SLA was significant as the leaves are markedly thicker in the upper part of the crown compared with the lower part. The short-root specific area (SRA) in the 30 cm topsoil was 182.9 ± 9.5 m2 kg−1, specific root length (SRL), root tissue density (RTD) and the number of short-root tips (>95% ectomycorrhizal) per dry mass unit of short roots were 145.3 ± 8.6 m g−1, 58.6 ± 3.0 kg m−3 and 103.7 ± 5.5 tips mg−1, respectively. In August the amount of nitrogen, phosphorus and potassium, accumulated in above ground biomass, was 192.6, 25.0 and 56.6 kg ha−1, respectively. The annual flux of N and P retranslocation from the leaves to the other tree parts was 57.2 and 3.7 kg ha−1 yr−1 (55 and 27%), respectively, of which 29.1 kg ha−1 N and 2.8 kg ha−1 P were accumulated in the above-ground part of the stand.  相似文献   

4.
The effects of different planting densities (250,000, 500,000 and 750,000 plants ha−1) and cutting frequencies (45, 60 and 75 days) on the biomass production and chemical composition of Moringa oleifera was studied in a completely randomised split plot design with four blocks, in Managua, Nicaragua, located geographically at 12°08′15′′ N and 86°09′36′′ E. The 75 day cutting frequency produced the highest fresh matter yield, 100.7 and 57.4 Mg ha−1 year−1, and dry matter (DM) yield, 24.7 and 10.4 Mg ha−1 year−1, during the first and second year, respectively. All planting densities produced the highest DM yield at 75 day cutting frequency. In the first year, the density of 750,000 plants ha−1 produced the highest fresh matter yield, 88.0 Mg ha−1 and highest DM yield, 18.9 Mg ha−1, but in the second year the density of 500,000 plants ha−1 gave the highest yields, 46.2 Mg ha−1 and 8.1 Mg ha−1, respectively. During the first year, DM (22.8%), neutral detergent fibre (NDF) (30.8%) and ash (9.14%) contents were highest and in vitro DM digestibility (IVDMD) (68.2%) was lowest in the longest cutting interval, while contents of crude protein (CP) (22.8%) and acid detergent fibre (ADF) (22.8%) were not affected significantly by cutting frequency. In the second year, DM and CP contents and IVDMD were not significantly affected by cutting frequency, whereas NDF, ADF and ash contents were lowest in the 60 day cutting frequency. Planting density had no significant effect on chemical composition or IVDMD. These data suggest that Moringa forage could be an interesting protein supplement for ruminants.  相似文献   

5.
A large initial stocking × fertilizer factorial field trial established in 1993 with a Eucalyptus urophylla × grandis hybrid clone in southern Guangxi province, China, included 6 initial stocking treatments ranging from 667 to 2,222 trees ha−1 and 6 fertilizer treatments. Growth data was collected at various intervals up to age 192 months and also data on outer-wood pilodyn penetration (as an indicator of wood density) and acoustic velocity through the outer-wood (as an indicator of modulus of elasticity) at the last assessment. This report examines the results for the main effect of initial stocking treatments and stocking × fertilizer interactions across ages. There were significant differences between initial stockings for both average individual tree volume and standing volume ha−1 at all ages up to 144 months, but just average individual tree volume at 192 months. At ages up to 75 months total standing volume decreased as initial stocking decreased—maximum volume being obtained at 2,222 trees ha−1. From 88 to 110 months the highest standing volume was obtained at 1,667 trees ha−1 and then at ages 144 and 192 months, 833 trees ha−1 provided the highest standing volume. Average individual tree volume at all ages generally increased as initial stocking decreased—the largest trees were obtained at 667 trees ha−1. As age increased the proportional differences between tree volumes at higher and lower stockings increased—at age 27 months average individual tree volume at 667 trees ha−1 was 72% greater than that at 2,222 trees ha−1 and differences increased steadily with age up to 190% at 192 months. There were no significant differences between initial stockings for the properties of the outer-wood assessed by pilodyn penetration and acoustic velocity. Also, no significant interactions were found between initial stocking and fertilizer treatments for any traits at any ages implying that effects of initial stocking and fertilizer are additive for the traits assessed.  相似文献   

6.
Crop and livestock production in the Guinea savanna zone of northern Ghana has been declining over the past years as a result of increasing pressure on land. To sustain soil productivity, pigeon pea(Cajanus cajan), a leguminous perennial crop was evaluated for its potential as a short duration fallow crop for fodder and grain, and maize (Zea mays)production. It involved comparing a natural fallow (i.e., control) and four improved fallows of pigeon pea pruned annually at 30 cm, 60 cm and 90 cm from the ground, and unpruned pigeon pea over a two-year period. After this time, the land was cleared manually and planted to maize. The highest mean annual biomass of pigeon pea over the two-year period of 6.1 t ha−1 dry matter (DM) was obtained by pruning at 60 cm. The highest leaf litter production and pigeon pea seed yield was obtained from the no pruning treatment. The mean maize grain yield from the improved fallow (3.02 t ha−1) in the first year after clearing was significantly (P < 0.05) greater than that of the natural fallow (1.54 t ha−1). Considering the biomass of pigeon pea from pruning, pigeon pea seed yield and maize grain yield after the pigeon pea, pruning pigeon pea at 60 cm is the most promising regime for crop-livestock production systems. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   

7.
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  相似文献   

8.
The browse potential of black locust (Robinia pseudoacacia L.) and thornless honey locust [Gleditsia triacanthos f. inermis (L.) Zabel] has not been adequately tested. Our objective was to determine effects of fertilization and pollarding on biomass and foliar nutritive value in separate studies of black locust and thornless honey locust in Arkansas, USA. Shoots were sampled monthly for two consecutive growing seasons in 2002 and 2003 to determine foliar, shoot, and total aboveground biomass, shoot basal diameter, and foliar nutritive value (crude protein and in vitro digestibility). Black locust yielded more foliar biomass when pollarded at 50 or 100 cm and fertilized with 600 kg P ha−1, than at 5 cm with or without P, averaging 3.5 Mg dry matter ha−1. Black locust foliar crude protein and in vitro dry matter digestibility ( ≤ 170 and 534 g kg−1, respectively) decreased as leaves aged, but still met maintenance needs for beef cattle (Bos taurus L.). Thornless honey locust had little agronomic potential because of slow establishment, low foliar yield (330 kg ha−1), and a 2% reversion to undesirable thorny phenotype. Black locust should be considered for livestock browse when drought induces semi-dormancy of herbaceous forages.  相似文献   

9.
欧阳华 《林业研究》1995,6(1):27-38
INTRODUCTIoNChangesinsoilNmineralizationratescouIdbeanearlywarningofsoilNavaila-bilityoreventualforestdeclinesinceNisoftenan.importantnutrientforgrowth(Keeneyl98O;Leaetal.l982;Vitouseketal-l982).Nitrogenmineralizationinvolvestwodistinctprocessesfammonification,inwhichNH:isformedfromorganiccom-pounds,andnitrification,theoxidationofNH:toNO3.ManystudiesofatmosphericdepositionimpactsonforestshavetargetedsoilNmineraIizationusingsimulatedaciddepositionundercontrolledlaboratoryconditions(T…  相似文献   

10.
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   

11.
Acacia senegal, the gum arabic-producing tree, is the most important component of traditional dryland agroforestry systems in the␣Sudan. The spatial arrangement of trees and the type of agricultural crop used influence the interaction between trees and crops. Tree and crop growth, gum and crop yields and nutrient cycling were investigated over a period of 4 years. Trees were grown at 5 × 5 m and 10 × 10 m spacing alone or in mixtures with sorghum or sesame. No statistically significant differences in sorghum or sesame yields between the intercropping and control treatments were observed (mean values were 1.54 and 1.54 t ha−1 for sorghum grain and 0.36 and 0.42 t ha−1 for sesame seed in the mixed and mono-crop plots, respectively). At an early stage of agroforestry system management, A. senegal had no detrimental effect on crop yield; however, the pattern of resource capture by trees and crops may change as the system matures. A significant positive relationship existed between the second gum picking and the total gum yield. The second gum picking seems to be a decisive factor in gum production and could be used as an indicator for the prediction of the total gum yield. Soil organic carbon, N, P and K contents were not increased by agroforestry as compared to the initial levels. Soil OC was not increased by agroforestry as compared to sole cropping. There was no evidence that P increased in the topsoil as the agroforestry plantations aged. At a stocking density of 400 trees ha−1 (5 × 5 m spacing), A. senegal accumulated in its biomass a total of 18.0, 1.21, 7.8 and 972 kg ha−1 of N, P, K and OC, respectively. Agroforestry contributed ca. 217 and 1500 kg ha−1 of K and OC, respectively, to the top 25-cm of soil during the first four years of intercropping.  相似文献   

12.
This article compares three methods for forest resource estimation based on remote sensing features extracted from Airborne laser scanning and CIR orthophotos. The estimation was made exemplarily for the total stem volume of trees for a given area, measured in cubic metres per hectare [m3 ha−1] (as one of the most important quantitative parameters to characterise a forest stand). The following methods were compared: Regression Analysis (RA), k-NN (nearest neighbour) method and a method that utilises regional yield tables, referred to as the yield table method (YT-method). The estimation of stem volume was examined in a mixed forest in Southern Germany using 300 circular inventory plots, each with a size of 452 m2. Remote sensing features relating to vegetation height and structures were extracted and used as input variables in the different approaches. The accuracy of the estimation was analysed using scatter plots and quantified using absolute and relative root mean square errors (RMSE). The comparison was made for all plots, as well as for averaged plot values located within forest stands that have the same age class. On “plot level” the RMSE yielded 79.79 m3 ha−1 (RA), 81.93 m3 ha−1 (k-NN) and 81.78 m3 ha−1 (YT-method) and for the averaged values 35.75 m3 ha−1 (RA), 35.06 m3 ha−1 (k-NN) and 42.98 m3 ha−1 (YT-method). Advantages and disadvantages, as well as requirements, of the methods are discussed.  相似文献   

13.
On-farm experiments were conducted in the Philippines to study over a 4-year period the growth of two timber trees, gmelina (Gmelina arborea R. Br.) and bagras (Eucalyptus deglupta Blume), and their impact on the grain yield of intercropped maize. The experiment consisted of maize monocropping plots (control) and maize intercropped between trees planted in block (2 × 2.5 m), and hedgerow arrangement (1 × 10 m). Three maize crops were planted in the block plots before canopy closure, and seven maize crops were planted in the hedgerow and monocropping plots. Maize grain yield in the hedgerow and in the block arrangement with gmelina were respectively 37% (16.58 tons ha−1) and 68% (8.3 tons ha−1) lower than in monocropping (26.21 tons ha−1). In the plots with bagras, maize grain yield in hedgerow and in block arrangement were respectively 19% (24.8 tons ha−1) and 66% (10.4 tons ha−1) lower than in monocropping (30.6 tons ha−1). For both tree species, the diameter at breast height (dbh) was greater in hedgerow than in block arrangement, with the difference being more pronounced with age. It was estimated that gmelina planted in hedgerows would produce 6–8 m3 ha−1 of merchantable volume more than if planted in block. The study verifies the hypothesis that intercropping between widely-spaced trees rows (planted at 10 m or more) is more profitable and feasible to smallholders than either maize monocropping or woodlots, and concludes with recommendations on how to further improve the productivity of tree-intercropping systems.  相似文献   

14.
Soil nutrient depletion as a result of continuous cultivation of soils without adequate addition of external inputs is a major challenge in the highlands of Kenya. An experiment was set up in Meru South District, Kenya in 2000 to investigate the effects of different soil-incorporated organic (manure, Tithonia diversifolia, Calliandra calothyrsus, Leucaena leucocephala) and mineral fertilizer inputs on maize yield, and soil chemical properties over seven seasons. On average, tithonia treatments (with or without half recommended rate of mineral fertilizer) gave the highest grain yield (5.5 and 5.4 Mg ha−1 respectively) while the control treatment gave the lowest yield (1.5 Mg ha−1). After 2 years of trial implementation, total soil carbon and nitrogen contents were improved with the application of organic residues, and manure in particular improved soil calcium content. Results of the economic analysis indicated that on average across the seven seasons, tithonia with half recommended rate of mineral fertilizer treatment recorded the highest net benefit (USD 787 ha−1) while the control recorded the lowest (USD 272 ha−1). However, returns to labor or benefit-cost ratios were in most cases not significantly improved when organic materials were used.  相似文献   

15.
The importance of agroforestry systems in CO2 mitigation has become recognized worldwide in recent years. However, little is known about carbon (C) sequestered in poplar intercropping systems. The main objective of this study is to compare the effects of three poplar intercropping designs (configuration A: 250 trees ha−1; configuration B: 167 trees ha−1 and configuration C: 94 trees ha−1) and two intercropping systems (wheat–corn cropping system and wheat–soybean cropping system) on biomass production and C stocks in poplar intercropping systems. The experiment was conducted at Suqian Ecological Demonstration Garden of fast-growing poplar plantations in northwestern Jiangsu. A significant difference in C concentration was observed among the poplar biomass components investigated (P ≤ 0.05), with the highest value in stemwood and the lowest in fine roots, ranging from 459.9 to 526.7 g kg−1. There was also a significant difference in C concentration among the different crop components (P ≤ 0.05), and the highest concentration was observed in the corn ear. Over the 5-year period, the total poplar biomass increased with increasing tree density, ranging from 8.77 to 15.12 t ha−1, while annual biomass production among the crops ranged from 4.69 to 16.58 t ha−1 in the three configurations. Overall, total C stock in the poplar intercropping system was affected by configurations and cropping systems, and configuration A obtained the largest total C stock, reaching 16.7 t C ha−1 for the wheat–soybean cropping system and 18.9 t C ha−1 for the wheat–corn cropping system. Results from this case study suggest that configuration A was a relative optimum poplar intercropping system both for economic benefits and for C sequestration.  相似文献   

16.
Green manure of multipurpose trees is known to be a good source of nutrients to crop. However, most agroforestry species do not have adequate phosphorus (P) in their leaves. Supplementing green manure with moderate dose of P is a beneficial strategy to improve food security in Rwanda. This study examines the effects of Calliandra calothyrsus Meissner, Tithonia diversifolia Hensley A.Gray and Tephrosia vogelii Hook.f. green manure applied independently or in combination with triple super phosphate (TSP) and lime on maize yield and P uptake in the Oxic Tropudalf of Rubona, Rwanda. The treatments were the control, lime at 2.5 t ha−1, TSP at 25 and 50 kg P ha−1, leaf of C. calothyrsus, T. diversifolia, and T. vogelii each at 25 and 50 kg P ha−1, respectively. Leaf shrubs biomass, TSP and lime were applied for four consecutive seasons (2001–2004). The results showed that the combination of green manure with TSP at a rate of 50 kg P ha−1 significantly increased maize yield from 24 to 508% when compared to the control and T. divesifolia combined with TSP was leading (508%). Equally, the same treatments as indicated above showed higher P uptake (15.6–18. 6 kg P ha−1) than the control (5 kg P ha−1) and 65% of maize yields variation was explained by total P uptake. The plant residues quality such as C:N ratio, total plant N, and P significantly influenced the variability of maize grain yields.  相似文献   

17.
Possibilities for intercropping cinnamon (Cinnamomum verum J.Pres) under rubber (Hevea brasiliensis Muell. Arg.) were investigated. In one experiment, the 9.1 m inter row space of a 15 year old rubber plantation was intercropped with cinnamon. The effect of four cinnamon densities (17,500 bushes ha−1, 8,260 bushes ha−1, 7,980 bushes ha−1 and 3,980 bushes ha−1) and four levels of fertilizer (60 g bush−1, 120 g bush−1, 180 g bush−1 and 240 g bush−1) on cinnamon bark yield and yield components were tested in a split plot experiment. Interception of light by the rubber canopy, R:FR ratio of transmitted light under the rubber canopy and the fine root length density in the inter row was uniform in all treatments throughout the whole experimental period. R:FR ratio of light under cinnamon was significantly lower under the highest cinnamon plant density of 17,500 bushes ha−1. Bushes in the highest plant density treatment (D1) produced longer shoots than those in the lowest density treatment (D4), where the weight of bark cm−1 was greater. As a result there were no significant effects of plant density on cinnamon bark yield at the individual bush level. This also resulted in significantly greater weight of bark per ha in the highest density treatment (D1) indicating the possibility of increasing cinnamon plant density for obtaining greater bark yield from intercropping systems under considerable shade and root competition. Increasing the level of added fertilizer even up to four times the standard did not have any advantage on bark yield or its components.  相似文献   

18.
The efficiency of the botanical insecticide (BI) NeemAzal T/S (containing 1% Azadirachtin A), on the basis of azadirachtin applied in a dose of 20 g a.i. ha−1 against Brassica pod midge (Dasineura brassicae), has been monitored for 4 years. The biological efficiency of BI was compared with the efficiency of some synthetic insecticides. It was ascertained that BI was very efficient in decreasing the number of damaged oilseed rape pods (ranging from 56.5 to 85.9% compared to untreated plants) and its efficiency was comparable with synthetic insecticides based on Chloronicotinyl (Thiacloprid) and Neonicotinoid (Acetamiprid). BI’s efficiency was, in some years, even significantly higher compared to pyrethroid (λ-cyhalothrin). The high biological efficiency of azadirachtin that we ascertained was significantly reflected in increasing potential crop yields. The yield increase of azadirachtin ranged between 9.3 and 19.4% compared to the control sample. Azadirachtin showed the highest yield for the whole time of experimentation, and in some years the yield increase was significantly higher compared to some synthetic agents.  相似文献   

19.
Silvopastoral systems involving poplars are widespread in rural landscapes in a number of regions of New Zealand. The effect of widely spaced trees of Populus nigra × P. maximowiczii, aged 8–11 years, on the growth and botanical composition of understorey pasture mixes was determined over 3 years at a southern North Island hill country site. Pasture mixes comprised existing pasture, and two introduced test swards comprising new grass (Agrostis capillaris, Dactylis glomerata, Lolium perenne) and legume (Lotus uliginosus, Trifolium repens) cultivars. Pasture accumulation beneath trees (6.6 t DM ha−1 year−1) was 23% less than open (unshaded, no trees) pasture (8.6 t DM ha−1 year−1) and differences in accumulation occurred between tree aspects (North and South sides of trees) when trees were foliated. In early spring, North plots produced 11–14% more herbage than South plots whereas in late summer, South plots produced up to 44% more herbage than North plots. Yield of both test swards (6.4 and 8.0 t DM ha−1 year−1) was not significantly different from that of the existing sward (7.4 t DM ha−1 year−1) but productivity varied between swards in spring and summer. One test sward included Lotus uliginosus cv. Grasslands Maku, and the sward produced 30% more DM than the other swards in mid-summer. Dactylis glomerata cv. Grasslands Wana comprised 37% of the DM of swards in which it was sown and was the most successful cultivar, followed by Grasslands Maku. Both cultivars are recommended for silvopastoral systems where pasture is lightly grazed.  相似文献   

20.
The study was carried out in a 9-year-old hinoki cypress (Chamaecyparis obtusa (Sieb. et Zucc.) Endl.), stand over a span of three years from July 1992 to June 1995, primarily to predict litter production from exteral tree dimensions by combining open-top clothtrap and clipping methods. Litter production was virtually concentrated in October and November. Stem cross-sectional area at the crown base was proved to be the reliable predictor of litter production, and that single regression model was evolved irrespective of year. The regression model had proportional constants of 2.696 × 10−2 and 3.540 × 10−2 kg cm−2 year−1 for leaf litter and total litter production, respectively. Utilizing the model, leaf litter production of the stand was assessed to be 5.04, 5.12, and 4.99, and total litter production to be 6.48, 6.58, and 6.40 Mg ha−1 year−1 for the first, second and third year, respectively. Biomass increment was 6.67, 7.80, and 7.70, tree mortality was 0.15, 0.13, and 0.41, and insect grazing was 0.09, 0.05, and 0.002 Mg ha−1 year−1 for the first, second and third year, respectively. Above-groud net production was therefore 13.39, 14.55, and 14.51, Mg ha−1 year−1, and biomass accumulation ratio (biomass/net production) was 1.86, 2.21, and 2.76 year for the first, second and third year, respectively. Considering data from earlier studies and the results of this study, biomass accumulation ratio,BAR (year), of hinoki stands was best related to above-ground biomass,y (Mg ha−1), using the power function:BAR=0.112y 0.936. Excluding seedling stands, leaf efficiency (above-ground net production per unit leaf mass) of hinoki stands was 0.91±0.02 (SE) Mg Mg−1 year−1, irrespective of stand biomass or age.  相似文献   

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