Home gardens and Dioscorea species – A case study from the climatic zones of Sri Lanka

Home gardens are considered as vital units for enhancing food security particularly in developing nations of South Asia, such as Sri Lanka. Although the yam crop Dioscorea spp. constitute a popular but still minor component in Sri Lankan home gardens, they have the potential of producing large quantities of edible material with minimal inputs. However, their real value in South Asian home gardens is not yet reported. Hence, this study was carried out to get insights into home garden characteristics, gardener demography as well as current management practices within 300 Sri Lankan home garden systems that are located along a climatic gradient. By using interviews and field observations, gardeners, who cultivated in particular Dioscorea species, were studied within 10 of the 25 administrative districts distributed in the wet, intermediate and dry climatic zone of Sri Lanka. Furthermore, current management practices of yams cultivation were analyzed on local scale and compared afterwards with management recommendations published in the year 2006 by the Department of Agriculture. Dioscorea species were found in a majority of home gardens, especially in wet and intermediate zones of Sri Lanka. D. alata was the most prominent species and was managed at a subsistence level and not as per recommendations developed by the Department of Agriculture. Our results revealed that Dioscorea alata is an essential component of Sri Lankan home gardens in rural areas and can yield substantial quantities of edible tubers with low input, especially during times of food scarcities, and has therefore the potential to enhance food security and rural development

Green manuring for tropical organic cropping – A comparative analysis

Green manuring is an essential component of tropical organic farming. Field studies evaluated the use of three legumes as in situ or ex situ green manures, along with a nonlegume green manure and a control to ascertain their impacts on soil properties and yields of maize and mung bean grown in major (wet) and minor (dry) seasons. In situ green manuring, especially with legumes, had the most beneficial impact on soil properties, while with ex situ methods, the use of leaves alone improved soil properties. Yields were increased to a greater extent by green manuring in the minor season, and the in situ system proved to be more beneficial. In ex situ green manuring, greater benefits were obtained by the application of leaves alone. The impact of different green manures and their application methods is presented

Growth, yields and nitrogen use of open pollinated and hybrid maize (Zea mays L) as affected by organic matter and its placement in minor seasons of Asia

Sustainable maize (Zea mays L) production in smallholder cropping systems of South Asia require combinations of organic matter and mineral fertilizers, especially nitrogen, when the crop is subjected to water stress in the minor seasons. As the cultivation of hybrid maze is being promoted in these nations, field studies over two minor seasons evaluated the impact of three types of common organic materials and their method on incorporation on root growth, seeds yields and nitrogen use patterns of an open pollinated (OPV) and a hybrid variety of maize. The growth and yields of the OPV were higher than those of the hybrid, illustrating the greater adaptability of this variety to the drier conditions of minor seasons. The least beneficial impact of organic matter on growth, yield and nitrogen use was with rice straw, a low quality organic matter, while Tithonia leaves promoted root growth. Application of Gliricidia leaves produced the highest yields followed by the use of Tithonia. N use patterns were enhanced to similar extents by the addition of Tithonia and Gliricidia leaves, and the beneficial impact was greater than when rice straw was used. Incorporation enhanced the benefits of the organic matter, especially in the hybrid, which produced lower yields, which is considered less adaptable to the environments of this season. The benefits of using good quality organic matter and its incorporation on maize growth, productivity and the utilization patterns of nitrogen in the minor dry seasons of South Asia was evident in this field study

Impact of associated intercrops on growth and yield of maize (Zea mays L) in major seasons of south Asia

Mixed cropping is a feature of smallholder tropical farming systems, and maize (Zea mays L) is the most common highland cereal planted in these systems in Asia, under rainfed conditions. A field study thus determined the effect of intercropping maize with four popular food crops, over two major seasons of tropical Asia. The bean (Phaseolus spp.) intercrop had no significant impact on growth and yields of maize, while cassava (Manihot esculenta) had the most significant adverse effect. The impact of tomato(Lycospersicon esculentum) and sweet potato (Ipomoea batatas) on maize was in-between those of beans and cassava. The bean, tomato and sweet potato – maize intercrops have LER values greater than unity, while that of cassava maize was lower than 1. Optimizing maize production and resource use in smallholder systems through mixed or intercropping thus requires the selection of suitable crop species

Multiseason recoveries of organic and inorganic nitrogen-15 in tropical cropping systems

In tropical agroecosystems, limited N availability remains a major impediment to increasing yield. A 15N-recovery experiment was conducted in 13 diverse tropical agroecosystems. The objectives were to determine the total recovery of one single 15N application of inorganic or organic N during three to six growing seasons and to establish whether the losses of N are governed by universal principles. Between 7 and 58% (average of 21%) of crop N uptake duringthe first growing season was derived from fertilizer. On average, 79% of crop N was derived from the soil. When 15N-labeled residues were applied, in the first growing season 4% of crop N was derived from the residues. Average recoveries of 15N- labeled fertilizer and residue in crops after the first growing season were 33 and 7%, respectively. Corresponding recoveries in the soil were 38 and 71 %. An additional 6% of the fertilizer and 9.1 % of the residue was recovered by crops during subsequent growing seasons. There were no significant differences in total 15N recovery (average 54%) between N from fertilizer and N from residue. After five growing seasons, more residue N (40%) than fertilizer N (18%) was recovered in the soil, better sustaining the soil organic matter N content. Long-term total recoveries of 15N-labeled fertilizer or residue in the crop and soil were similar. Soil N remained the primary source of N for crops. As higher rainfall and temperature tend to cause higher N losses, management practices to improve N use efficiency and reduce losses in wet tropical regions will remain a challenge

Building Organic Bridges', at the Organic World Congress

Abstract Field studies evaluated the impact of three common organic materials added with or without Effective Microorganisms (EM)and its derivative EMFPE on yields and disease incidence in organic potatoes (Solanum tuberosum

Building Organic Bridges', at the Organic World Congress

Abstrac

Building Organic Bridges', at the Organic World Congress

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Organic matter addition in organic farming – Impact on root development and yields in maize and cowpea over dry seasons

Organic matter and its proper management are vital in tropical organic farming to maintain productivity. A field study thus placed rice straw or Gliricidia leaves on the soil surface or the material was incorporated into soil. The impact of these treatments on soil moisture, root development and yields of organically grown maize or cowpea were evaluated in an Asian dry season. Incorporation increased soil moisture retention in the soil and hence induced better root growth, culminating in higher yields. The impact was greater in maize, especially with Gliricidia leaves. The benefits of incorporating organic matter in dry seasons for tropical organic farming are presented

Growth and Nutrient Use Efficiencies of Yams (Dioscorea spp.) Grown in Two Contrasting Soils of West Africa

Fertilization is an important management strategy of yams (Dioscorea spp.) especially when grown in degraded soils. A field study evaluated the leaf numbers, leaf area indices, crop growth, yields, and nitrogen (N) and potassium (K) use efficiencies of D. alata and D. rotundata in Côte d'Ivoire when grown in two contrasting soils with and without fertilizer. D. alata had a lower number of leaves per vine, although leaf area indices were higher, and the leaves were retained for a longer period than in D. rotundata. In all situations, the yields of D. alata were significantly higher, and fertilizers promoted growth of shoots, roots, tubers, and, thus, final yields especially in the low fertile savanna soil. The beneficial impact of fertilizer on yields was significantly lower in the fertile forest soils. The nutrient use agronomic efficiencies indicated the impact of both N and K in promoting yields especially under nonfertilized conditions