Balanço do nitrogênio e fósforo em solo com cultivo orgânico de hortaliças após a incorporação de biomassa de guandu.

Os objetivos deste trabalho foram avaliar os efeitos de faixas de guandu (Cajanus cajan) e da incorporação da biomassa proveniente de sua poda na fertilidade do solo e na produtividade de três hortaliças sob cultivo orgânico. O delineamento usado foi de blocos casualizados completos em esquema de parcelas subsubdivididas com três repetições. As produtividades de beterraba, cenoura e feijão-de-vagem não foram afetadas pelos tratamentos. Nas parcelas onde não houve incorporação da biomassa de guandu, o balanço de nitrogênio no sistema foi negativo, ao passo que com a incorporação, esse balanço foi positivo. Embora tenha ocorrido balanço positivo para o fósforo nas parcelas sem a incorporação de biomassa de guandu, houve um aumento significativo na absorção desse elemento pelas hortaliças quando o material foi incorporado. O sistema de cultivo em aléias de guandu pode representar uma prática vantajosa para os produtores orgânicos, por contribuir na manutenção da fertilidade do solo

On-farm research methods for alley cropping

Meeting: International Workshop on Alley Farming in the Humid and Subhumid Tropics, 10-14 Mar. 1986, Ibadan, NGIn IDL-282

Effect of seedbed preparation method and mulch on soil physical properties and yield of cowpea in a rice fallow of an inland valley swamp

The effects of three seedbed preparation methods: mounds, minimum (handhoe) tillage and zero tillage; and two residue management methods: application of 4 Mg ha- ' of rice straw mulch and no mulch on soil physical properties and yield of cowpea ( Vigna unguiculata (L.) Walp.) were studied in a rice fallow of an inland valley swamp in central Nigeria during the dry seasons of 1988 and 1989. Soil physical properties measured were particle size distribution, bulk density, soil water retention, penetrometer resistance, pore size distribution, soil temperature and wetness. In general, soil compaction was such that zero tillage >> minimum tillage = mounds. The proportion of macropores in the 0-0.05 m depth was 18%, 35.2% and 42.0%, with zero tillage, minimum tillage and mounds, respectively. Diurnal soil temperatures and soil wetness were highest and lowest, respectively, on mounds, and lowest and highest, respectively, with zero tillage. Mulching had no effect on compaction but decreased diurnal soil temperature and increased wetness. The combination of zero tillage and mulch resulted in a wet, cool and compacted seedbed, whereas the warmest, driest and most porous seedbed was the bare mound. Grain yield of cowpea was not significantly affected by seedbed preparation method. Seedbed preparation methods which increase porosity and are not labour-intensive (e.g. minimum tillage) are, therefore, more appropriate for cowpea production in inland valley swamps. Mulching was effective in increasing yield, only when rainfall occurred prior to the onset of reproductive growth in cowpea such that yield was increased by 36% in 1988, but not in 1989. However, rainfall analyses indicate that moderate amounts of rainfall are likely to occur during the latter part of the dry season when reproductive growth of cowpea takes place. The least risky and hence, most appropriate soil management system for dry-season cowpea production in rice fallows of inland valley swamps is, therefore, a combination of minimum tillage and mulch

RESPONSE OF SELECTED VEGETABLE CROPS TO SALINE WATER IN THE U.S. VIRGIN ISLANDS

A series of greenhouse experiments was conducted to determine the effects of different sea water concentrations (0, 10, 20, 40, and 80%) on the growth of tomatoes (Lycopersicon esculentum L. var. Heatwave), bell pepper (Capsicum annuum L. var. California Wonder), and sweet basil (Ocimum basilicum L.) at two different statges of growth (seedling and reproductive). Results indicated that each of the crops can tolerate different levels of saline water without significant reduction in growth. Tomatoes exhibited tolerance to 40% sea water at the seedling stage and 20% at the reproductive stage. Bell peppers were tolerant to 20% sea water at the seedling stage and 40% at the reproductive stage. Basil displayed tolerance to 40% sea water at the seedling stage and 80% at the reproductive stage. In all experiments, the electrical conductivity (EC) of soil extracts increased with increasing concentration of sea water. This study would suggest that at certain concentration, saline water can be utilized to irrigate selected vegetable and herb crops with economic importance in the Virgin Islands