Physical and chemical properties of an oxisol after maize cropping on rotation with leguminous plants / Propriedades físicas e químicas de um latossolo ver melho durante o cultivo do milho após rotação com plantas leguminosas

Crop rotation has been a daily management to ensure viability of no-tillage system; however, it is few accepted and practiced by farmers. Thus, this study aims to establish a crop rotation scheme in soil quality. Consequently, cover crops of dwarf mucuna, pigeon pea dwarf, sun hemp and maize were cropped in 2010 under no-tillage system. Soil properties were determined prior their beginning, after the management of cover crops and maize harvest. Results were submitted to ANOVA and averages were compared. The macroporosity and total porosity answered to the adopted management with some variation. So, cover crops need much time to express their potential, mainly related to the physical characteristics of the studied soil. Chemical properties are susceptible to this management since higher changes were observed after management with cover crops. This crop rotation in a long term may allow the maintenance of soil quality because it avoids losses of nutrients and carbon

A rotação de culturas é ação básica para garantir a viabilidade do sistema plantio direto, porém, é pouco aceita e praticada pelos agricultores. Assim, este trabalho teve por objetivo estabelecer o esquema de rotação de culturas sobre a qualidade do solo. Para isso, sob sistema plantio direto, foramimplantadas, em 2010, as plantas de cobertura mucuna anã, feijão guandu anão, crotalaria juncea, e a cultura do milho. As propriedades do solo foram determinadas anteriormente à implantação, após o manejo da cobertura vegetal e após a colheita do milho. Os resultados encontrados foram submetidos à análise de variância e a comparação de médias. As plantas de cobertura podem precisar de mais tempo para que expressem seu potencial, principalmente relacionado às características físicas do solo, embora tenha sido observada variação da porosidade total e macroporosidade. As propriedades químicas são sensíveis ao manejo empregado, já que maiores alterações foram observadas após o manejo com as plantas de cobertura. Mesmo que não possibilite aumento significativo no teor de C no solo, o uso desta rotação, em longo prazo, poderá permitir a manutenção da qualidade do solo, evitando perdas de nutrientes e carbono

Produção de biomassa e composição química de adubos verdes cultivados no vale do ribeira / Biomass production e chemical composition of green manure cultivated in vale do ribeira

A contribuição da adubação verde com leguminosas para melhoria do solo e produção agrícola depende em primeiro lugar da produção de biomassa e da sua composição química, que variam em função da espécie, região e estação de cultivo. Objetivo do presente trabalho foi avaliar a composição química da biomassa produzida por adubos verdes no Vale do Ribeira, São Paulo, Brasil. Para tal, foi conduzido um experimento em Pariquera-Açu-SP, no ano agrícola 2006/2007, em blocos casualizados, com quatro tratamentos (três adubos verdes e vegetação espontânea) e cinco repetições. Aos 30, 60, 90 e 120 dias após a semeadura, foram coletadas amostras em 1 m² da parte aérea das plantas e determinada a matéria fresca e seca, bem como a composição da biomassa. Crotalária, guandu e mucuna produziram, em ordem decrescente, as maiores quantidades de biomassa e foram mais eficientes do que a vegetação espontânea. A biomassa produzida pelos adubos verdes apresentou qualidade superior à produzida pela vegetação espontânea. Crotalária e guandu apresentam maior proporção de matéria seca acumulada no caule que possui baixo teor de N, alta relação C/N e L/N, variáveis que tornam a decomposição dos resíduos mais lenta. A análise particionada da matéria seca permite indicação mais precisa da composição química dos resíduos e a previsão da disponibilidade dos nutrientes no solo.

The contribution of green manure to soil improvement and crop production depends primarily on biomass production and its chemical composition, which vary depending on the species, region and growing season. The aim of this research was to evaluate the chemical composition of biomass produced by green manures in Vale do Ribeira, São Paulo, Brazil. In order to develop this research, was carried an experiment in Pariquera-Açu, in 2006/2007, in completely randomized blocks design with four treatments (three green manure and spontaneous vegetation) and five replications. At 30, 60, 90 and 120 after sowing samples were collected in 1m2 of the shoots and determined fresh and dry, and chemical composition biomass. Sunhemp, pigeon pea and mucuna produced, in decreasing order, the largest quantities of biomass and were more efficient than the spontaneous vegetation. The biomass produced by green manure had higher quality than that produced by spontaneous vegetation. Sunhemp and pigeon pea have a higher proportion of dry matter in stems which have low N, high C/N and L/N ratio, variables indicating slow decomposition of residues. The analysis of dry matter partitioned to better indication of the chemical composition of the residues and the prevision of the availability of nutrients in the soil.

Effect of Castor and Velvetbean Organic Amendments on Meloidogyne arenaria in Greenhouse Experiments.

Effectiveness of castor (Ricinus communis) and velvetbean (Mucuna deeringiana) amendments was tested for suppression of the root-knot nematode (Meloidogyne arenaria) and growth of okra (Hibiscus esculentus) in three greenhouse experiments. Regression analysis was used to relate nematode population data or plant growth responses to various rates (0, 1, 2, 4, or 8 g/560 cm(3) soil pot) of each amendment in separate experiments. In general, plant growth parameters responded positively to the amendment rate until a level of about 4 g to 5 g of velvetbean or castor amendment/pot. Similar trends were observed for nematode galls, egg masses, and second-stage juveniles extracted from root systems. In most circumstances, quadratic equations best expressed the relationships between plant or nematode parameters and rates of velvetbean or castor amendment, leading to the assumption that a best rate of the amendment for plant growth or nematode suppression can be predicted. In a third experiment, in which both amendments were compared directly, velvetbean amendment was more efficient than castor in suppressing nematodes as well as in improving plant growth.

Responses of Meloidogyne arenaria and M. incognita to Green Manures and Supplemental Urea in Glasshouse Culture.

The recent loss of many effective nematicides has led to renewed interest in alternative methods of nematode management. Greenhouse experiments were conducted to determine the effects of rapeseed and velvetbean green manures, and supplemental urea, on the root-knot nematodes Meloidogyne arenaria and M. incognita. Green manures were incorporated with M. arenaria-infested soil using rates totaling 200,300, and 400 mg N/kg soil. Squash plants grown in this soil were evaluated using a gall index and plant dry weight. A second experiment tested ratios of rapeseed green manure to urea resulting in rates of 50, 100, and 150 mg N/kg soil on viability ofM. incognita eggs and degree of galling on squash test plants. A third experiment examined combinations of velvetbean green manure and urea resulting in rates of 100, 200, and 300 mg N/kg soil on viability of M. incognita eggs. When applied at rates of 200, 300, and 400 mg N/kg soil, rapeseed green manure was more effective than velvetbean green manure at reducing galling of squash roots caused by M. arenaria. Decreased viability of M. incognita eggs was observed from treatments that received rates >/= 1200 mg N/kg soil with higher percentages of N from urea.

Effect of Tropical Rotation Crops on Meloidogyne incognita and Other Plant-Parasitic Nematodes.

In a field experiment conducted on sandy soil in Florida during the 1993 season, rotation crops of castor (Ricinus communis), velvetbean (Mucuna deeringina), 'Mississippi Silver' cowpea (Vigna unguiculata), American jointvetch (Aeschynomene americana), 'Dehapine 51' cotton (Gossypium hirsutum), and 'SX-17' sorghum-sudangrass (Sorghum bicolor x S. sudanense) were effective in maintaining low population densities (<12/100 cm(3) soil) of Meloidogyne incognita race 1, whereas high population densities (>450/100 cm(3) soil) resulted after 'Clemson Spineless' okra (Hibiscus esculentus) and 'Kirby' soybean (Glycine max). Following a winter cover crop of rye (Secale cereale), densities of M. incognita following the six most effective rotation crops (1993 season) remained relatively low (

Effects of Tropical Rotation Crops on Meloidogyne arenaria Population Densities and Vegetable Yields in Microplots.

The effects of 12 summer crop rotation treatments on population densities of Meloidogyne arenaria race 1 and on yields of subsequent spring vegetable crops were determined in microplots. The crop sequence was: (i) rotation crops during summer 1991 ; (ii) cover crop of rye (Secale cereale) during winter 1991-92; (iii) squash (Cucurbita pepo) during spring 1992; (iv) rotation crops during summer 1992; (v) rye during winter 1992-93; (vi) eggplant (Solanum melongena) during spring 1993. The 12 rotation treatments were castor (Ricinus communis), cotton (Gossypium hirsutum), velvetbean (Mucuna deeringiana), crotalaria (Crotalaria spectabilis), fallow, hairy indigo (Indigofera hirsuta), American jointvetch (Aeschynomene americana), sorghum-sudangrass (Sorghum bicolor x S. sudanense), soybean (Glycine max), horsebean (Canavalia ensiformis), sesame (Sesamum indicum), and peanut (Arachis hypogaea). Compared to peanut, the first eight rotation treatments resulted in lower (P

Tropical rotation crops influence nematode densities and vegetable yields.

The effects of eight summer rotation crops on nematode densities and yields of subsequent spring vegetable crops were determined in field studies conducted in north Florida from 1991 to 1993. The crop sequence was as follows: (i) rotation crops during summer 1991; (ii) cover crop of rye (Secale cereale) during winter 1991-92; (iii) 'Lemondrop L' squash (Cucurbita pepo) during spring 1992; (iv) rotation crops during summer 1992; (v) rye during winter 1992-93; (vi) 'Classic' eggplant (Solanum melongena) during spring 1993. The eight summer crop rotation treatments were as follows: 'Hale' castor (Ricinus communis), velvetbean (Mucuna deeringiana), sesame (Sesamum indicum), American jointvetch (Aeschynomene americana), weed fallow, 'SX- 17' sorghum-sudangrass (Sorghum bicolor x S. sudanense), 'Kirby' soybean (Glycine max), and 'Clemson Spineless' okra (Hibiscus esculentus) as a control. Rotations with castor, velvetbean, American jointvetch, and sorghum-sudangrass were most effective in maintaining the lowest population densities of Meloidogyne spp. (a mixture of M. incognita race 1 and M. arenaria race 1), but Paratrichodorus minor built up in the sorghum-sudangrass rotation. Yield of squash was lower (P

Velvetbean in Rotation with Soybean for Management of Heterodera glycines and Meloidogyne arenaria.

The effect of previous crops - soybean (Glycine max) or velvetbean (Mucuna deeringiana) - and aldicarb on yield and nematode numbers for selected soybean cultivars was studied in a field infested with a mixture of Meloidogyne arenaria and Heterodera glycines. Soybean following velvetbean yielded 959 kg/ha more than soybean following soybean. Nematicide treatment resulted in increased yield, and there was no interaction between nematicide treatment and previous crop. Cultivars interacted significantly with nematicide treatment but not with previous crop for yield. Velvetbean reduced numbers of H. glycines but not M. arenaria. Cultivars interacted with previous crop, and the previous crop x nematicide x cultivar interaction was significant for both M. arenaria and H. glycines. We concluded that velvetbean is effective in reducing yield losses caused by mixed populations of M. arenaria and H. glycines, regardless of genetic resistance of soybean cultivar.

Crop Rotation Studies with Velvetbean (Mucuna deeringiana) for the Management of Meloidogyne spp.

Results from a greenhouse experiment at Cabrils, Spain, with two velvetbean (Mucuna deeringiana) accessions (Florida and Mozambique) growing in sterilized sandy loam and inoculated with Meloidogyne arenaria race 2, M. incognita race 1, and M. javanica revealed that the legume was not a host for these nematodes. In contrast, roots of 'Clemson Spineless' okra (Hibiscus esculentum), 'Summer Crookneck' squash (Cucurbita pepo), and 'Davis' soybean (Glycine max) were galled by all three root-knot nematodes. Greenhouse experiments at Auburn, Alabama, using soils infested with Heterodera glycines (race 14) + M. incognita or with H. glycines + M. arenaria (race 2) showed that, in contrast to Davis soybean, a Mexican and the Florida velvetbean accessions were not hosts for the nematodes. An experiment with 'Florunner' peanut (Arachis hypogaea) and the Florida velvetbean in a field infested with M. arenaria (race 1), near Headland, Alabama, showed that significant juvenile populations of the nematode at peanut harvest time were present only in plots with peanut. A microplot rotation experiment demonstrated that 'Black Beauty' eggplant (Solanum melongena) following the Florida velvetbean had heavier shoots and lower numbers of M. arenaria juveniles in the roots and in the soil than eggplant after Summer Crookneck squash or Davis soybean.

Comparison of nematode population densities on six summer crops at seven sites in north Florida.

Densities of plant-parasitic nematodes were compared on six crops grown for forage during the summer of 1991 at seven sites in north central Florida. The cropping treatments were 'Howard' soybean (Glycine max), 'Deltapine 105' soybean, velvetbean (Mucuna deeringiana), 'California Blackeye #5' cowpea (Vigna unguiculata), 'Pioneer 3098' tropical corn (Zea mays), and 'Asgrow Chaparral' sorghum (Sorghum bicolor). Highest final densities (Pf) of Meloidogyne incognita and Criconemella spp. were obtained following corn or sorghum at most sites. The lowest Pf of M. incognita occurred after velvetbean at all seven sites, but Pf after cowpea were equivalent to Pf after velvetbean at four of seven sites. Cultivar choice is critical in planning rotations to suppress M. incognita because results obtained here and elsewhere have shown great differences among sorghum and cowpea cultivars. The Pf of Pratylenchus spp. were lowest following velvetbean at four of seven sites. There were no differences in densities of Paratrichodorus minor among crops, but populations increased at a greater rate if initial density (Pi) was low. Multiplication rates (Pf/Pi) of most nematode species on most crops varied inversely with Pi. An accurate impression of nematode multiplication and host status could not be obtained unless a range of Pi was examined.