Clean Weeding Research Articles

Clean weeding showed positive effects on earthworm communities following six years of minimum tillage in a maize field in northern Zimbabwe

ABSTRACT Earthworms are a major component of soil fauna communities with positive effects on soil chemical, biological and physical processes. A study was carried out to investigate the medium-term effects of cultural practices on earthworm communities in an agricultural field. Data were collected in the 2018/2019 cropping season from a six-year-old experiment with tillage system, fertiliser application rate and weeding intensity as the main, sub- and sub-subplots, respectively. Lumbricus (34.4%) and Diplocardia (38.3%) were the dominant genera, while endogeic earthworms (48.4%) dominated the community structure among other earthworm functional groups. Clean weeded plots under the basin planting system had higher Lumbricus abundance (quadruple), genus richness (76.4%) and Shannon diversity index (56.0%) than all other treatments. Inorganic fertiliser application in the conventional tillage system reduced Eisenia abundance and genus evenness by 100.0% and 73.3%, respectively. These results suggest that in minimum tillage systems, frequent hand weeding confers positive effects on earthworms including increased abundance. In conventional tillage systems, application of high doses of inorganic fertiliser is detrimental to earthworm communities. Further studies need to focus on identifying the most sustainable and cost-effective hand weeding frequency for enhanced earthworm diversity and increased crop productivity.

Developing sustainable pepper smallholders in the East Luwu regency, South Sulawesi province

Sustainable agriculture aims to improve productivity, conserve the environment, promote social welfare, and improve economic efficiency. The productivity of white pepper smallholders in East Luwu Regency, South Sulawesi, was the highest in Indonesia at 1.4 tons/ha, and some smallholders reached more than 6 tons/ha. This research aimed to study the cultivation practices and evaluate sustainability from an environmental, social, and economic perspective. The method used in this research was a case-study on accomplished smallholders in Ranteangin Village, Towuti District. Pepper smallholders’ outstanding cultivation practices that threaten sustainability from environmental and social perspectives were clean land clearing, monoculture planting pattern, utilization of wood supports, clean weeding, and processing. While from an economic perspective, most cultivation practices were sustainable because the higher cost incurred can be offset by higher productivity. Strategies to develop sustainable cultivation practices are implementing more appropriate technologies such as minimum tillage application, multispecies planting of cover crops, live tree supports, and waste treatment in product processing.

PENGARUH POPULASI TANAMAN DAN PENGGUNAAN MULSA TERHADAP POPULASI GULMA DAN HASIL PUCIL JAGUNG MANIS (ZEA MAYS SACCHARATA STURT) DI LAHAN KERING

This study was conducted in Balai Benih Induk (BBI) Luwus, Baturiti District, Tabanan Regency, with the high of place 506m above sea level occurring in March to May 2014. This research used randomized block design arranged per factor, namely population of plants (P) including three steps: P1=80.000 plants per hectare, P2= 100.00 plants per hectare, P3= 120.000 per hectare; and mulch (M) that include: M0= without mulch and without cleaning, M1= without mulch with clean weeding, M2= rice plants straw mulch (5 ton per hectare) and M3= black silver plastic mulch. Eventually, there were 12 combination treatments, each of which was repeated 3 times to obtain 36 land slots. The research indicates that there was no real interaction between the treatment of plant population and mulch usage in all variables observed. The 100.000 plant population per hectare can produce the weight of dry and fresh oven corn kernel without highest cornhusk that was to say 4.79 tons and 0.53 tons or 11.66 % and 20.45% higher compared to 120.000 plant population per hectare. The use of black silver plastic and rice plants straw mulch can produce the weight of fresh and dry oven corn kernel without cornhusk per hectare each of which is 4.69 tons, 4.57 tons, and 0.54 tons, 0.47 tons or 26.76%, 38.46 %, and 23.51 %, 20.51 % higher than without mulch and without clean weeding. Clean weeding treatment can produce the weight of fresh and dry oven corn kernel without cornhusk per hectare with its weight of 4.63 tons and 0.51 tons or 25.35 % and 35.90 % higher than without mulch and cleaning. Clean weeding treatment was not obviously different from mulch treatment. The identification of weed types were 19 kinds of weeds and Cyperus rotundus L. Weeds. They have the highest density and each absolute frequent of 1249.333 stems m-2 and 1.00.

Germinable weed seed-bank response to plant residue application and hand weeding under two contrasting tillage systems in a granite-derived clay loam soil in Zimbabwe

High levels of weed infestation are among the major reasons for the limited adoption of conservation agriculture techniques by farmers in sub-Saharan Africa. This study investigated the effects of plant residue application (zero: NR, low: LR, medium: MR and high: HR) and hand weeding (twice: TWI, thrice: THR, four times: FOU and clean weeding: CLE) under two tillage systems (basin planting: BASIN, and conventional tillage: CT) on weed seed density in a clay loam soil at Chinhoyi University of Technology experimental farm, Zimbabwe. During 2014/15, the number of germinable Amaranthus hybridus L. seeds was higher in BASIN+NR+THR and BASIN+MR+TWI than other treatments. Germinable propagules of Cyperus L. spp. were fewer in NR+FOU and NR+CLE than NR+TWI and NR+THR plots. In 2015/16, TWI resulted in an increase of 52.3−79.5% of the number of germinable A. hybridus seeds compared to THR, FOU and CLE. Germinable weed seeds increased by 67.1% for Alternanthera pungens Kunth and 164.8% for Galinsoga parviflora Cav. in the surface compared to the subsurface layers of BASIN but were evenly distributed in CT. The results suggest that cultural practices exert selection pressure on individual weed species which may change the weed species composition in the soil seed bank.

Analysis of woody plants dimensions on the affected and restricted land management practices in Sudan Vegetation Zone, Adamawa State, Nigeria

Human activities have transformed the vegetal environment into affected and restricted areas with varied woodland dimensions. The aim of the study is to identify the difference in distributions, heights, girths and bole lengths of native woody plants on continuous cultivation, fallow and reserve lands of Hong Local Government Area in 2018. Data on woody plants distributions, heights, girths and bole lengths were generated from the field using quadrat samples and measuring tape. Stratified sampling technique was adopted to cover the study area while purposively sampling method was adopted to establish the sample quadrats on the three dissimilar land management practices adopted. Variance was used to analyze the data while ‘F’ distribution at 0.05% confidence limit was used to test for the significance. From the result, there are 181 woody plant stands observed on the 12 sample plots (1800m2). The woodland distributions vary from 17, 13 and 1 on fallow, reserve and continuous cultivation lands on 100m2. The tallest (11.37m) woodlands are on continuous cultivation land followed by the reserve (10.20m) while the shortest (2.58m) is on fallow land. The girths vary from 1.89m, 1.03m and 0.23m on continuous cultivation, reserve and fallow lands respectively. The stems are 4.34m, 2.53m and 0.80m for reserve, continuous cultivation and fallow lands. For significant increase in tree distributions farmers should preserve seedlings during annual clearing and clean weeding as well adopt longer fallow period. The result implies with increase in human activities such as arable farming and wood harvesting lead to decrease in plant distribution and vice versa.Keywords: Land management practices, Native woodlands, Savanna region, woodland dimensions

Combing K-means Clustering and Local Weighted Maximum Discriminant Projections for Weed Species Recognition

Abstract: Weed species identification is the premise to control weeds in smart agriculture. It is a challenging topic to control weeds in field, because the weeds in field are quite various and irregular with complex background. An identification method of weed species in crop field is proposed based on Grabcut and local discriminant projections (LWMDP) algorithm. First, Grabcut is used to remove the most background and K-means clustering (KMC) is utilized to segment weeds from the whole image. Then, LWMDP is employed to extract the low-dimensional discriminant features. Finally, the support vector machine (SVM) classifier is adopted to identify weed species. The characteristics of the method are that (1) Grabcut and KMC utilize the texture (color) information and boundary (contrast) information in the image to remove the most of background and obtain the clean weed image, which can reduce the burden of the subsequent feature extraction; (2) LWMDP aims to seek a transformation by the training samples, such that in the low-dimensional feature subspace, the different-class data points are mapped as far as possible while the within-class data points are projected as close as possible, and the matrix inverse computation is ignored in the generalized eigenvalue problem, thus the small sample size (SSS) problem is avoided naturally. The experimental results on the dataset of the weed species images show that the proposed method is effective for weed identification species, and can preliminarily meet the requirements of multi-row spraying of crop based on machine vision.

Influence of tillage, fertiliser regime and weeding frequency on germinable weed seed bank in a subhumid environment in Zimbabwe

Minimum tillage (MT) under conservation agriculture (CA), fertiliser application and weeding frequency influence weed seed-bank dynamics in cropping systems. A study was conducted at the Chinhoyi University of Technology farm, Zimbabwe during the 2014/15 and 2015/16 cropping seasons to investigate the influence of tillage, fertiliser and weeding on weed seed-bank dynamics. A field experiment arranged in a split-split plot randomised complete block design with three replications was used. Tillage (conventional tillage [CT] and MT), fertiliser application (zero, low, medium and high) and weeding frequency (twice, four times and clean) were the main plot, subplot and sub-subplot factors, respectively. Minimum tillage decreased Nicandra physalodes (L.) Gaertn. and Leucas martinicensis (Jacq.) R.Br. germinable seeds by up to 40% compared with CT. Germinable seeds of Amaranthus hybridus L. and Galinsoga parviflora Cav. were more frequent in high than medium fertiliser plots. Weeding four times resulted in more weed seeds than weeding twice and clean weeding. Results of this study suggest that some problem weeds, including N. physalodes, are likely to be reduced, whereas Iopmoea plebeia R.Br. may be persistent under MT. The results further suggest that weeding four times created conditions that were favourable for rapid weed seed germination, weed growth and possible seed return.

English

Seaweed Kappaphycus alvarezii previously known as Eucheuma cottonii is one of the best sources of kappa carrageenan and is cultivated in Philippines, Indonesia, Malaysia and other countries including India. In the present study, semi-refined carrageenan (SRC) was prepared from K. alvarezii with different concentrations of KOH (6, 12, 18 and 24%) at 80 ± 2°C for 2 h; its sulfate contents were 13.73±0.74, 13.66±0.27, 13.84±0.66 and 14.76±0.18%, respectively, and it was 14.10±0.34% for untreated clean weed (control). The sulfate removal with increasing concentration of KOH used for processing SRC is not statistically significant (p < 0.05). The KCl gel strength of untreated clean weed and 6, 12, 18 and 24% KOH treated weed was 97±10.27, 650±12.11, 637±10.25, 552±18.71 and 526±26.55 g cm-2, respectively. Contents of 3,6-anhydrogalactose were 28.30±0.52, 33.41±0.50, 32.97±0.42, 31.15±0.60 and 31.61±0.17%. FTIR spectroscopy showed that molecules in all four SRC samples are quite similar. Spectral band was at 1257 cm-1 which referred to ester sulfate of 930 cm-1 for 3,6 anhydrogalactose and 848 cm-1 assigned to galactose-4-sulfate. From the present investigation, it was observed that sulfate removal and quality improvement with increasing concentration of KOH for cooking seaweed is not statistically significant; therefore, seaweed can be subjected to lower concentration of KOH treatment (6 to 12%) to produce semi-refined carrageenan on commercial scale. Key words: Seaweed, Kappaphycus alvarezii, KOH treatment, semi-refined carrageenan (SRC), sulfate content, FTIR spectra, gel strength.

PENGARUH WAKTU PENYIANGAN TERHADAP PERTUMBUHAN DAN PRODUKSI BEBERAPA VARIETAS SORGUM (Sorgum bicolor (L.) Moench)

ABSTRACTThis study aims to know the effect of weeding time on the growth and production of some varietiesof sorghum in Pasar 1 street Tanjung Sari, Medan, with ± 25 meters altitude above the sea level inJuly – November 2012. The design use Factorial Separated Design Frame with 2 aspects. The firstaspect as a main frame is variety (Sangkur, Kawali, Numbu) and the second factor as subordinateframe is weeding time (clean weeding during research, weeded after 7 days planting, weeded after 14days planting, weeded after 21 days planting, weeded after 28 days planting, without weedingprocess). The parameters measured were plant height, number of leaves, flowering, canopy wetweight, production per sample, production per plot, the production per ha, the weight of 1000 seeds.From the research, varieties significantly affect on plant height (4-8 weeks after planting), number ofleaves (6 and 8 weeks after planting), flowering, canopy wet weight, production per sample,production per plot, production per hectare, weight 1000 seeds.Weeding time significantly affect onplant height (4-8 weeks after planting) the number of leaves (2-8 weeks after planting), the weight ofthe wet canopy, production per sample, production per plot, production per hectare, the weight of1000 seeds. Interaction significantly affect on the number of leaves 6 weeks after planting.Keywords : sorghum, varieties, and weeding time

Coberturas do solo sobre a amplitude térmica e a produtividade de pimentão

Com o objetivo de avaliar o efeito dos sistemas de plantio direto e convencional e estratégias de manejo de plantas daninhas na variação da temperatura do solo e na produtividade de pimentão, realizou-se, na Universidade Federal do Semiárido, em Mossoró-RN, um experimento no esquema de parcelas subdivididas, distribuídas no delineamento experimental em blocos casualizados com quatro repetições. Os sistemas de plantio direto e convencional do pimentão foram avaliados nas parcelas; nas subparcelas, avaliaram-se três estratégias de manejo de plantas daninhas (cobertura do solo com filme de polietileno preto, com capinas e sem capinas). Em cada subparcela foram instalados sensores tipo termopares, a 5 cm de profundidade, para medir a temperatura do solo. A partir dos dados obtidos, determinou-se a variação da temperatura ao longo do dia, no período de 20 a 30 dias após o plantio das mudas de pimentão, e a cada cinco dias, a média das temperaturas máxima e mínima e a amplitude térmica diária. Aos 60 e 147 dias após o transplante das mudas de pimentão, foram feitas avaliações da densidade e massa seca de plantas daninhas nos tratamentos sem capinas. Os tratamentos com filme de polietileno e capinado no sistema de plantio convencional apresentaram elevação na temperatura máxima diária do solo em 6,7 e 5,0 ºC, respectivamente, em relação ao sistema de plantio direto com capinas. A amplitude térmica no sistema de plantio convencional nos tratamentos com capinas regulares e com filme de polietileno foi de 11 ºC, ao passo que no sistema de plantio direto a amplitude foi de 6,3, 4,5 e 4,0 ºC nos tratamentos com capinas, sem capinas e com filme de polietileno, respectivamente. A interferência das plantas daninhas nos tratamentos sem capinas resultou em redução de 94,95 e 92,10% da produtividade comercial nos sistemas de plantio direto e convencional, respectivamente.

Abundance of Metioche Vittalicollis ( Orthoptera:Gryllidae) and Natural Enemies in A Rice Agroecosystem as Influenced by Weed Species

Weeds in the rice fields impact the population of M. vittaticollis and several predators on rice habitat. A study was conducted during rainy season 2004-2005 and dry season 2005, which selective weeding and weed strips were applied. In selective weeding, Monochoria vaginalis, Fimbristylis miliacea, Cyperus iria, and Limnocharis flava were left, and made a weed strip at the periphery of rice plot which was consisted of those four species. Clean weeding as farmers usually do was also applied as a control treatment. Results showed that the presence of weed plant species in the earlier planting season of dry season 2005 tended to maintain the population of the predatory insects of rice pests, in particularly M. vittaticollis and Anaxipha longipennis. Population of Ophionea nigrofasciata, Paederus spp. and Micraspis inops were not different among the treatment plots during rainy season (2004-2005) and dry season (2005). The species number of predator and parasitoids seemed to increase slower in the clean weeded plot in comparing with the species number in selectively weeded or weeds strips plot at early planting season. Rice yield in the experimental plots were not significantly different. Some weeds in the rice fields may not have adverse effects on rice productivity. Keywords : generalist predator, weeding, predatory cricket

KEMAMPUAN KOMPETISI BEBERAPA VARIETAS KEDELAI (GLYCINE MAX) TERHADAP GULMA ALANG-ALANG (IMPERATA CYLINDRICA) DAN TEKI (CYPERUS ROTUNDUS):

The objective of this research was to study response of the growth and yield on soybean varieties against Imperata cylindrica and Cyperus rotundus competition and to study competitive ability of soybean varieties against Imperata cylindrica and Cyperus rotundus. The experimental research was conducted at Karangsari Village, Kembaran, Banyumas. The experiment used a Randomized Completely Block Design with 2 factors and 4 replications. Factor 1. Soybean Variety, consisted of Grobogan, Ijen and Sinabung, Factor 2. Weed, consisted of clean weeding, Imperata cylindrica 50 weeds/m2 and Cyperus rotundus 50 weeds/m2. The result showed that Ijen and Sinabung caused the better growth than Grobogan. Sinabung caused the highest for the amount of polong per plant : 285.5 and the seed weight per plant : 46.6667 g. Sinabung caused the best competitive ability than Grobogan and Ijen, its showed that the highest competition value. The competition of Sinabung-Cyperus rotundus caused competition value : 15.0075, whereas the competition of Sinabung-Imperata cylindrica caused competition value : 7.9913.

Effect of weed control methods on some soil properties of a newly planted cocoa farm

Weed control constitutes a high percentage of the total field maintenance cost of newly planted cocoa. Soil samples were collected from an experiment that was designed to evaluate some weed control methods during cocoa establishment. The objective of the experiment was to assess the effect of the weed control methods on microbial biomass and extractable N and P contents of the cocoa-growing soil during cocoa establishment. The weed control treatments were clean weeding, two times per year; clean weeding, three times per year; clean weeding, four times per year (recommended practice); high slashing, four times per year; clean weeding (1 m wide), three times per year plus Mucuna pruriens cover crop; clean weeding, three times per year plus Flemingia congesta mulch; Gramoxone 1.5 l ha-1, four times per year; and Roundup 1.5 l ha-1, three times per year arranged in a randomized complete block design. Microbial biomass N content ranged from 10.8 to 42.5 mg N kg–1 soil. Microbial biomass N was significantly higher (P

TWO METHODS OF COMPOSTING GIN TRASH

The ginning of cotton (Gossypium hirsutum L.) results in the accumulation of approximately 90 kg of gin trash per bale of cotton ginned. In the past, disposal of raw gin trash was by burning, land application and feeding to livestock, but problems with clean air standards, weed seeds and diseases, and chemical residues, respectively, make each of these methods unacceptable. Composting the gin trash would alleviate certain problems associated with land application on farm fields. Experiments were conducted to investigate windrow composting. A split plot experiment with five reps was initiated to evaluate turning times, nitrogen (N) fertilization and bacterial inoculation. Composite samples were collected and analyzed for nutrients and selected chemicals. Another experiment was established to compare timing and physical methods of turning windrows. The Lipsey®-gin-trash-composting system was investigated by sampling three compost piles at three different cotton gins. The chemical composition and weed seed germination were investigated. Results indicate that windrow composting does not solve the weed seed or plant disease problem; otherwise, the product was satisfactory. The Lipsey®-gin-trash-composting system resulted in a pile of material whose outside 0 to 15 cm depths contained viable weed seeds and disease organisms, but none survived below this exterior. This system resulted in an incomplete composting material with offensive odors.

Improved water control and crop management effects on lowland rice productivity in West Africa

Much of the rapidly-growing demand for rice in West Africa will be met from production in inland valley swamps which are abundant and relatively robust with regard to cropping intensification. Rice yields in the traditional, predominating non-bunded systems are low (about 1.5 Mg ha−1). Informal development of traditional rainfed lowlands is currently occurring across the region, mainly with low-cost interventions such as the building of field bunds. Relating lowland rice yield to quantitative information on resource base quality and agronomic practices will improve future research priorities and guide site and system-specific targeting of available technical options. Diagnostic on-farm trials were conducted in 62 traditional and 40 improved (bunded) rainfed lowland fields in three agro-ecological zones of Cote d'Ivoire (Guinea savanna, bimodal forest, and monomodal forest zones) to quantify effects of improved water control on productivity. Weed biomass and rice grain yield were determined in farmers' fields and in super-imposed researcher-managed subplots (clean weeding, zero N control treatment, and mineral fertilizer N application). Grain yield variability was attributed to agronomic practices using multiple regression analysis. Bunding significantly increased rice grain yield across sites by about 40% and controlled weeds, with approximately 25% less weed biomass in bunded than in open plots. Mineral fertilizer N application significantly increased rice yields (18% on average across sites) only in bunded fields, where N use efficiency was 12 compared to 4 kg of rice grain per kg of applied N in open fields. Across environments, about 60% of the observed variability in rice grain yields was explained by water control and the timing of agronomic management interventions (weeding, N application). The increased development of lowland rice areas through the construction of field bunds has the potential to significantly increase rice production in West Africa, while also possibly reducing labor requirements for hand weeding and allowing for a more efficient use of mineral N fertilizers. The benefits from construction of bunds are likely to be largest in the relatively well-drained inland valleys of the savanna and bimodal rainfall forest, compared to the high-rainfall monomodal forest zones.

Rice yield and productivity gaps in irrigated systems of the forest zone of Côte d'Ivoire

Much of the rapidly growing demand for rice in West Africa will be met from increased production in irrigated lowlands, which cover about 12% of the regional rice-growing area. A large potential for expansion of irrigated areas exists particularly in the inland valleys of the humid forest zone. Current production is characterized by large variability in productivity, management practices and production constraints. Quantifying the variability in rice yield and identifying the determining factors are prerequisites to the development of site-specific recommendations and to improved targeting of technologies. Diagnostic on-farm trials were conducted on 64 irrigated lowland fields in the humid forest zone of southern Côte d'Ivoire, in 1995–1996. This was a part of the regional gradient study of irrigated systems from the desert margin to the humid forest zone. Cropping calendars, field operations and input use were monitored. Weed biomass, rice N uptake, and grain yield were determined in farmers' fields as well as in super-imposed, researcher-managed subplots (clean weeding, no N control, and mineral fertilizer N application). Rice yield potential was simulated by using the Oryza-S crop growth model. Yield losses were attributed to management factors based on performance of rice in researcher-managed subplots (management-related yield gap) and by multiple regression with management options. Grain yields varied between 0.2 and 7.3 Mg ha −1 with mean yields of 3.2 in partially and 4.2 Mg ha −1 in fully irrigated systems, 44% and 57% of the potential yield of 7.3 Mg ha −1, respectively. Age of seedlings at transplanting, timeliness of operations and application of P fertilizer were correlated to yield and explained 60% of the observed variability. Grain yield was correlated with N uptake ( r 2 = 0.93 ***) but not with N application rate. Split application of mineral fertilizer N was associated with a 0.48 Mg ha −1 yield increase ( p = 0.002), regardless of the quantity applied. Additional weeding increased yield only in systems with imperfect irrigation. Weed biomass was reduced with improved water control and it increased with age of seedlings at transplanting, and was higher in direct-seeded than in transplanted rice. Echinochloa spp. were the most common weeds in fully irrigated systems and Panicum laxum was more common in the imperfectly irrigated fields. While improved water management was associated with substantial rice yield increases (1.16 Mg ha −1), the timeliness of transplanting, weeding and N fertilization appears to be the key to increased rice yields in the forest zone of West Africa.

Potential use of &lt;i&gt;Flemingia macrophylla&lt;/i&gt; as mulch for managing weeds in young cocoa in Ghana

The prospects for using Flemingia macrophylla and Mucuna pruriens in combination with manual weeding during the establishment of young cocoa was investigated. The following treatments were compared: Clean weeding three times/annum + F. macrophylla planted in the inter-rows of cocoa and biomass used as mulch; clean weeding of cocoa lines (1 m wide) three times/annum + Mucuna cover crop; and clean weeding four times/annum. The use of Flemingia mulch in combination with manual clean weeding three times/annum resulted in large girths and taller cocoa plants than in plots where Mucuna was used as cover crop. The girth and height of the young cocoa seedlings in the Flemingia plots were, however, not significantly different from those in plots where weeds were manually clean-weeded four times/annum. Seedling mortality was lower in the plots with F. macrophylla (7 per cent) than in plots which had Mucuna cover crop (13 per cent). Flowering and jorquette formation occurred earlier in the Flemingia plots than in the other treatments. The potential biological benefits of using F. macrophylla in an integrated weed management programme in young cocoa and the application cost are discussed. Ghana Jnl agric. Sci. Vol.31(1) 1998: 67-72

Growth and yield of maize alley cropped with Leucaena leucocephala and Faidherbia albida in Morogoro, Tanzania

This study examined the effect of alley cropping of Leucaena leucocephala and Faidherbia albida on wood biomass, maize grain yield and soil nitrogen status. The treatments were: trees planted alone at 1 × 5 m spacing; trees intercropped with maize and a sole maize crop. Mulch biomass averaged 6.18 and 0.97 t ha−1 for L. leucocephala and F. albida, respectively. Corresponding wood production was 1.71 and 1.11 t ha−1. Both total N and inorganic N (NO 3 − –N plus 4 + –N) were higher under F. albida and lowest under L. leucocephala. Similarly, foliar N concentration in maize was higher in plots intercropped with F. albida and least in L. leucocephala intercropping. Maize grain yield was little affected by the tree intercrop as competition for resources was reduced through periodic pruning and clean weeding. There was no gain in maize grain yield due to the presence of L. leucocephala and F. albida. These results suggest that alley cropping in Gario is justified for wood production but not for increasing maize grain yield.

Early growth of pigeonpea under open-pit planting and restricted weeding in semiarid Zimbabwe

Simple and efficient tree-establishment methods are a key to the success of agroforestry technologies under limited-resource conditions. An experiment was conducted to test the effect of open pit planting and reduced weeding on soil moisture content and growth of pigeonpea (Cajanus cajan (L.) Millsp.). The results indicated that open-pit planting might reduce early growth of the plant. Clean weeding gave the most rapid growth and should be practised in the first year of establishment. However, because circle weeding substantially increased basal diameter and branching when compared to no weeding, in situations with labour constraints, it can be used to lessen the deleterious effects of weeds.

Releasing Rain Forest Succession: A Case Study in the Dicranopteris linearis Fernlands of Sri Lanka

AbstractThroughout tropical moist climates, Dicranopteris linearis fernlands can develop as a result of rain forest clearance followed by frequent burning. In Sri Lanka, D. linearis fern‐lands are capable of suppressing the regeneration of rain forest. Field experiments were conducted at Sinharaja Man and Biosphere Reserve, a rain forest where fernlands occupy substantial areas of the reserve boundary. The experiment's objective was to identify methods for initiating forest regeneration in fernlands dominated by D. linearis Three disturbance treatments were used to initiate seedling regeneration: clean weed, root removal, and till. We hypothesized that increasing the severity of the soil disturbance would establish vegetation with higher species richness and diversity, greater above‐ground dry biomass, and higher percentage cover and seedling density. Results indicate only partial support for this hypothesis. Dry biomass was greatest in till treatments, the most severe soil disturbance. By comparison, species richness and diversity, seedling density, and percentage cover were greatest in root‐removal treatments, though in many instances the differences were not significant. The study clearly demonstrated that any kind of soil disturbance can facilitate the establishment of herbs, shrubs, and trees in a fernland dominated by D. linearis. Results showed that herbs, sedges, grasses, and pioneer shrubs represented greater proportions of seedling recruits than did pioneer trees. Seedlings of primary‐forest tree species were nearly nonexistent. In general, results showed that soil disturbance can play an important role in site preparation for the purpose of initiating non‐fern vegetation in fernlands dominated by D. linearis.