Leaf Mulch Research Articles

Allelopathic compounds in leaves ofGliricidia sepium (Jacq.) kunth ex walp. and its effect onSorghum vulgare L.

Allelochemicals fromGliricidia sepium were extracted, identified, and quantified using HPLC. Fifteen toxic compounds, namely gallic acid, protocatechuic acid,p-hydroxybenzoic acid, gentisic acid,Β-resorcyclic acid, vanillic acid, syringic acid,p-coumaric acid,m-coumaric acid,o-coumaric acid, ferulic acid, sinapinic acid (trans andcis forms), coumarin, and myricetin were identified and quantified. These compounds from the plant extracts were tested on the seeds of the crop plant,Sorghum vulgare. Rate of germination of the seeds and root elongation were found to be inhibited by the various compounds of the extract. Different quantities ofGliricidia leaf mulch, viz., 400, 800, and 1200 g/m(2) applied to theSorghum grown fields, were found to effectively control weeds. Mulching improved the total yield ofSorghum. Leaf manuring and mulching showed better crop yield when applied up to 800 g ofGliricidia leaf/m(2). Crop yield was better in mulch-applied fields when compared to the manure-applied ones.

Litterfall, litter decomposition and the use of mulch of four indigenous tree species in the Atlantic lowlands of Costa Rica

Litterfall, forest-floor litter biomass and nutrients, short-term litter decomposition and the effects of leaf mulches on initial growth of maize were studied for four indigenous tree species with agroforestry potential:Stryphnodendron microstachyum Poepp. et Endl.(S. excelsum), Vochysia ferruginea Mart,Vochysia guatemalensis Donn. Sm. (V. hondurensis) andHyeronima alchorneoides (O), growing in a young experimental plantation in the Atlantic humid lowlands of Costa Rica. Total annual leaf litterfall was higher inV. ferruginea plots, followed byS. microstachyum, V. guatemalensis andH. alchorneoides; all with values comparable to those reported for other tree species grown in agroforestry combinations in humid tropical regions. Forest-floor litter accumulation was highest underV. ferruginea andV. guatemalensis. Both litterfall and forest-floor litter material had similar patterns in nutrient concentrations: N was higher inS. microstachyum, Ca was higher inV. guatemalensis, K was higher inH. alchorneoides; Mg was higher inV. guatemalensis andH. alchorneoides; H. alchorneoides andV. guatemalensis had the highest P.V. ferruginea litter decomposed more slowly, whileS. microstachyum apparently decomposed faster than the other species. The twoVochysia species showed increases in N and P concentration in decomposing litter after seven weeks in the field,H. alchorneoides showed an increase in litter N and a decrease in litter P, andS. microstachyum showed a net decrease in both N and P over the same time period. The patterns found in the litter bag study were confirmed by results obtained in a tethered-leaves experiment.S. microstachyum andV. ferruginea litters lost more weight when mixed in a 1∶1 proportion than either of them alone. Maize seedlings growing in plots mulched withS. microstachyum andH. alchorneoides leaves showed greatest initial growth, confirming patterns found in decomposition and nutrient release studies. The results show that these species could be used in agroforestry combinations with different advantages according to the specific objectives desired, whether these are soil protection, nutrient recycling, or enhancement of the growth of associated crops.

Effects of mulching with multipurpose-tree prunings on soil and water run-off under semi-arid conditions in Kenya

The effect of adding leaf mulches ofGrevillea robusta, Cassia siamea andGliricidia sepium on the rate of soil and water run-off from a crop field were studied during two cropping seasons in an alfisol under semi-arid conditions at Machakos, Kenya. The experiment was conducted in a randomized complete block design with three replications; two rates of mulch of each species (2.24 t and 4.48 t, on dry matter basis, per ha) and a no-mulch control constituted the seven treatments. Soil and water run-off losses after each major rainfall event and the changes in ground and crop cover were measured. Rainfall erosivity and changes in soil bulk density and infiltration rate were also determined.

Morphological and chemotaxonomic identification of Blattella cockroaches (Blattaria : Blattellidae) from Taiwan and selected Pacific Basin locations

A total of 58 museum specimens of Blattella cockroaches from Taiwan was identified on the basis of traditional morphological traits. Cuticular hydrocarbon analysis was performed for each specimen by means of gas chromatography, and this was compared with morphology-based identifications. Additionally, 38 specimens captured at field sites were subjected to hydrocarbon analysis. Four of the five species known to occur in Taiwan were encountered. B. bisignata was the predominant species (n = 67), followed by B. lituricollis (n = 25). Other species included B. karnyi and B. sauteri. Although females of B. bisignata and B. lituricollis cannot be differentiated unequivocally on morphological traits, cuticular hydrocarbon profiles were markedly different, one profile clearly resembling those of male B. lituricollis. Patterns also were consistent among nymphal stages. Both species were found in dense ground covers of leaf litter and mulches in urban or rural settings, and in pure or mixed populations. Hydrocarbon profiles of B. bisignata from Hong Kong and Laos were consistent with those from Taiwan, based on ANOVA of KI (Kovats. Indices) 3010 and KI 3040 peak areas. These peaks comprise part of a novel homologous series of di, tri- and tetramethyl alkanes. Some geographic variation in specimens of B. lituricollis from Hawaii and Taiwan was noted. Chemotaxonomy has several advantages over traditional taxonomic procedures in separating closely-related species, or in identifying life stages when no morphology-based keys exist.

Evaluation of the Leaf of a Range of Tree Legumes as a Source of Nitrogen for Crop Growth

SUMMARYThe leaf mulch of the tree legumes Acacia cunninghamii, A. fimbriata, Calliandra calothyrsus, Gliricidia sepium, Leucaena leucocephala and Sesbania sesban was evaluated as a source of nitrogen for maize growth in glasshouse pot experiments. The mulch of Sesbania sesban resulted in the largest yields of maize stover but yields were less than those that resulted from application of equivalent rates of fertilizer nitrogen. The mulches of Gliricidia and Leucaena also produced a yield response in maize but those of Calliandra and the two Acacia species were ineffective as sources of nitrogen in the short term. Sesbania mulch at the equivalent of 5 t dry matter ha-1 produced a maize yield similar to that obtained with 75 kg N ha-1. The poor response to Calliandra and Acacia mulch may be associated with the high polyphenol and/or lignin content of the leaf of these species.

Residual soil moisture and wheat yield in relation to mulching and tillage during preceding rainfed crop

In two field trials on sandy loam (Fluvent) soil, maize stalk mulch, generated in situ and applied at maize harvest, conserved more soil moisture than did the fallow control or repeated ploughings and plankings. A sal leaf ( Shorea robusta) mulch at 10 t ha −1 was as effective as a maize stalk mulch, but had the disadvantage of cost and time incurred by its collection and transportation from the forest to the field. Combining tillage with mulching did not give any additional benefit. Maize stalk mulch, with or without tillage, conserved 35.6 and 63.6 mm more moisture per 450 mm of soil than did tillage treatments and fallow control in 1986–1987, between maize harvest and sowing of wheat. The corresponding moisture conservation in 1987 – 1987 was 16.8 and 26.0 mm, respectively. Mulch-induced residual soil moisture significantly increased the grain and straw yield of rainfed wheat. Wheat grain yield with a maize stalk mulch was 19% higher than with tillage treatments, and 52% higher than in the fallow control in 1986–1987. The corresponding increase in grain yield in 1987–1988 was 30 and 195%, respectively.

Woody legumes as live support systems in yam cultivation

This paper describes the effect of Gliricidia sepium, used as live support system on the development and tuber yield of Water Yam (Dioscorea alata). The leguminous perennial was planted in rows 3 m apart. The in-row distance between the trees was 1 m. In the alleys 2 rows of yam were planted, 1 m apart, with an in-row distance of 0.5 m. The aim of the experiment was to separate the effect of the leaf mulch produced by the trees, which was used to green-manure the yam crop, and the effect on the tuber yield that stems from the presence of the live stakes. Using Gliricidia sepium trees as live support more than doubles the yield per unit of area of yam; 8.8 ton ha"(yam sole-cropped, control) against 20.7 ton ha"(yam-tree association). Stak- ing explains slightly more of the yield increment than the mulch factor. The trees and the mulch derived create more favourable conditions for development of the yam plant, while the capability of the trees to extract nutrients from soil layers that can not be reached by the yam roots is demonstrated. It is proposed to select and breed yam cultivars directly in relation to suitable live support systems. Such integrated tree-annual crop systems potentially provide substitutes for the practice of shifting cultivation.

Woody legumes as live support systems in yam cultivation

This paper describes the effect of Gliricidia sepium, used as live support system on the development and tuber yield of Water Yam (Dioscorea alata). The leguminous perennial was planted in rows 3 m apart. The in-row distance between the trees was 1 m. In the alleys 2 rows of yam were planted, 1 m apart, with an in-row distance of 0.5 m. The aim of the experiment was to separate the effect of the leaf mulch produced by the trees, which was used to green-manure the yam crop, and the effect on the tuber yield that stems from the presence of the live stakes.

Effect of the application of the leaf mulch of Gliricidia sepium on early development, leaf nutrient contents and tuber yields of water yam (Dioscorea alata)

This paper describes the effects of the leaf mulch of Gliricidia sepium on the development and yield of Water Yam, Dioscorea alata. Using leaf mulch, the time taken for the yam setts to sprout can be shortened by approximately 20 percent.

The performance of selected leaf mulches in temperature reduction and moisture conservation in the upper soil stratum

This paper reports on the effect of the leaf mulches of Leucaena leucocephala, Gliricidia sepium and Flemingia macrophylla on moisture content and temperature in the first 5 cm of the soil. The mulches were applied at a standard quantity of 5,000 kg ha−1 DM.

The decomposition of the leaf mulches ofLeucaena leucocephala Gliricidia sepium andFlemingia macrophylla under humid tropical conditions

The decomposition of the leaf mulches ofLeucaena leecocephala, Gliricidia sepium andFlemingia macrophylla has been studied under field conditions. Mulch samples were analysed over a period of 70 days on carbon, nitrogen, phosphorus,potassium, calcium and magnesium left. Loss rates for the elements show similar patterns for the three mulches. Losses of mulch material are caused by decomposition as well as removal by soil-dwelling fauna (insects, arthropods, etc.) feeding on the mulch.

The performance of the leaf mulches ofLeucaena leucocephala, Flemingia macrophylla andGliricidia sepium in weed control

The performance of the leaf mulches ofLeucaena leucocephala, Gliricidia sepium andFlemingia macrophylla in weed control has been tested in two trials. The length of the period during which a mulch layer yields significantly less weedbiomass compared to the control plots is called the ‘effective life-span’ of the mulch.

Effects of orchard management practices on yield, quality and leaf nutrient content of Coorg mandarin

SummaryThe effects of orchard management practices such as clean cultivation, use of herbicides, digging once a year, sod culture and mulching were studied on the yield, quality and leaf nutrient content of ‘Coorg’ mandarin. Significant differences were observed in the weights and numbers of fruits, in total soluble sugars and in the ascorbic acid content of fruits. Dry-leaf mulching resulted in the maximum weight and numbers of fruits. Higher soil moisture retention was found with dry leaf mulching during the post-monsoon dry months at depths of 0–20, 20–40 and 40–60 cm. Higher leaf contents of N, K, Ca and Mg were recorded after dry-leaf mulching followed by the herbicide treatment. High leaf phosphorus was recorded in sod-culture.

Infiltration Rates and Sediment Production following Herbicide/Fire Brush Treatments

Termhtal infiltration rates were simiiar in soils on which a heavy whitebrush (Abysia lycioides) cover had been aerirny treated with 2 kg/ha (active ingredient) of 20% tebuthiuron pellets 4 years previously or on tebuthiuron-treated plots which had been prescribed burned the winter about 9 months prior to infiltration measurements, compared to untreated sites. However, sediment production was greater from plots treated with the herbicide than from areas subjected to the herbicide-fire system or from untreated plots. Only minor variations in infiltration rates occurred among sites originaiiy dominated by running mesquite (Prosopis reptuns) which were aerially sprayed with 2,4,5-T + picioram (1:l) at 1.1 kg/ha 3.5 years previously, burned 10 months previously, subjected to the herbicide-fire system or left untreated. However, sediment production on the running mesquite areas which had been sprayed tended to be greater than on untreated plots. Sediment production on areas subjected to the herbicide-prescribed burning system tended to be less than from brush-covered plots. Differences in sediment production In both experiments were generally attributed to siightly reduced mulch loads and mulch covers where the brush was removed as a leaf mulch donor by herbicide treatment. Prescribed burning apparently compensated for 10s~ of brush leaf mulch by promoting grass cover on herbicide-treated areas.

Haemogregarines in Snakes: The Incidence and Identity of the Erythrocytic Stages

The traditional methods of displaying reptile specimens in zoos provide ideal conditions for transmission of protozoan parasites due to the humid cage atmosphere and the sand or leaf mulch substrates used to simulate natu.ral habitats. These physical conditions favor arthropod reproduction; the concentration of potential hosts favors transmission of whatever parasites may be present. Indeed, the mortality rates typical of zoo reptile collections substantiate the probability that more than just the nutritional and psychological effects of confinement and display affect the longevity of the captive population. Only impractically elaborate precautions could eliminate the possibility of parasite transmission under the display conditions deemed necessary to assuage the aesthetic sensibilities of the general public. Therefore, examination of zoo specimens for parasites may be expected to be quite rewarding; seldom are conditions contributing to high parasite concentrations combined with the ready availability of hosts from all over the world that a zoo offers. This report presents data concerning the incidence and identity in captive snakes of the protozoan blood parasite generally included in the genus Haemnogregarina. These data were gathered during 1955 through 1958 as part of a program concerning experimental transmission of reptilian blood parasites. The authors are grateful to the curators of the reptile collections at the Lincoln Park Zoo, Chicago, Illinois, the Toledo Zoo, Toledo, Ohio, the Cleveland Municipal Zoo, Cleveland, Ohio, and to the zoo personnel at these institutions for their physical aid and moral support in the pursuit of the specimens from which blood and these data are taken.

THE ASSOCIATION OF DESERT ANNUALS WITH SHRUBS

IT HAS LONG been noted by both professional and lay observers that many species of annual plants characteristic of desert habitats are more or less strictly confined to sites beneath shrubs. Not all species of desert annuals are thus associated with shrubs. In fact, the herbs of a given area can be classified rather clearly into two groups, one nearly always growing beneath some species of shrubs, the other preponderantly occupying the broad expanses of otherwise bare soil between the widely-spaced shrubs. A few herbaceous species occur more or less indiscriminantly in both kinds of habitats. Furthermore, there are some species of shrubs that do not harbor dependent annual herbs or do so only rarely. The pattern of distribution is thus a very clear one comprising widely-spaced shrubs of several species, annual herbs growing between the shrubs, other annual species more or less confined to the bases of certain shrubs, and other shrub species which seldom or never harbor dependent herbs. This pattern of distribution and association of shrub and herb species was studied by Went (1942) in the Mojave Desert and in the Borego Valley of the Colorado Desert in Southern California. He showed a strong dependence of Malacothrix californica DC., Rafinesquia neomexicana Gray, Phacelia distans Benth., and Emmenanthe penduliflora Benth. upon sites provided by Franseria dumosa Gray, Larrea tridentata CoV., Opuntia echinocarpa Engelm. and Bigel., Hymenocloa salsola Torr. and Gray, and similar woody species. The shrub Encelia farinosa Gray, on the other hand, seldom harbored these annual herbs. He noted also that dead shrubs of any species harbored these herbs in abundance. Where the herbs were found apparently independent of shrubs, investigation invariably revealed a rotting stump of some dead shrub at the site of each. The failure of Encelic fctrinosa to harbor shrubdependent herbs was investigated by Gray and Bonner (1948a). They demonstrated in the leaves of Encelia a growth-inhibiting substance which, in either aqueous or ether extracts, killed tomato seedlings in water culture in 1-3 days. They showed also a marked depression of growth of tomato seedlings in sand culture by the application of Encelia leaves to the top of the sand and irrigation through the Encelia leaf mulch. It is suggested in their paper