Luiz Arnaldo Fernandes

Urease activity and its relation to soil organic matter, microbial biomass nitrogen and urea-nitrogen assimilation by maize in a Brazilian Oxisol under no-tillage and tillage systems.

Abstract We studied the relationship between urease activity (UA) and soil organic matter (SOM), microbial biomass N (Nbiom) content, and urea-N fertilizer assimilation by maize in a Dark Red Latosol (Typic Haplustox) cultivated for 9 years under no-tillage (NT), tillage with a disc plough (DP), and tillage with a moldboard plough (MP). Two soil depths were sampled (0–7.5 cm and 7.5–15 cm) at 4 different times during the crop cycle. Urea was applied at four different rates, ranging from 0 to 240 kg N ha–1. The levels of fertilizer N did not affect the UA, SOM content, and Nbiom content. No significant difference between the treatments (NT, DP, and MP) was observed for SOM during the experiment, probably because the major part of the SOM was in recalcitrant pools, since the area was previously cultivated (conventional tillage) for 20 years. The Nbiom content explained 97% and 69% of the variation in UA in the upper and deeper soil layer, respectively. UA and biomass N were significantly higher in the NT system compared to the DP and MP systems. The highest maize productivity and urea-N recovery was also observed for the NT system. We observed that the increase in urea-N losses under NT, possibly as a consequence of a higher UA, was compensated for by the increase in N immobilized in the biomass.

Fibra de coco e resíduo de algodão para substrato de mudas de tomateiro

A greenhouse experiment was carried out to evaluate fiber mixture of coconut and cotton waste, to produce substrate for tomato seedling production (cultivar Kada Gigante). The experimental design was randomized blocks, four replications, with seven treatments: T1) Commercial Substrate Hortimix®; T2) 0% coconut dry fiber mass (FC)+100% dry mass of cotton waste (RA); T3) 20% (FC)+80% (RA); T4) 40% (FC)+60% (RA); T5) 60% (FC)+40% (RA); T6) 80% (FC)+20% (RA); T7) 100% (FC)+0% (RA). The vigor was evaluated in terms of percentage and index of emergence, stem diameter, seedling height. Increasing the proportion of coconut fiber to cotton waste ratio resulted in an increase of percentage and index of emergence; however, the stem diameter, seedling height, shoot and root fresh and dry mass decreased. The residue of cotton proceeding from the compostage of residues of the textil factory, constitutes in a useful material in the commercial substrate production.

NPK fertilization on initial growth of physic nut seedlings in Quartzarenic Neossol

Balanced fertilization is important for plant growth. There is little information on physic nut (Jatropha curcas L.) and tests with the fertilization of the species are very recent. This study evaluated the initial growth of physic nut seedlings in response to NPK rates to Quartzarenic Neossol in a greenhouse and estimated P and K critical soil levels and N, P and K in shoot dry matter after 120 days of evaluation. The treatments were arranged in a randomized, fractional factorial design (4 x 4 x 4)1/2, totalizing 32 treatments with three replicates, 96 experimental plots and N rates (0, 75, 150 and 300 mg dm-3) as urea; P rates (0, 45, 90 and 180 mg dm-3) as triple superphosphate and K rates (0, 50, 100 and 200 mg dm-3) as potassium chloride. After 120 days, the plants were harvested and some variables evaluated: plant height, stem diameter, shoot and root dry weight, macro and micronutrient levels in plant shoots, and soil chemical properties. The physic nut seedlings responded to NPK fertilizer in the initial growth phase; the response to N was negative. The recommended P and K rates were 25 and 67 mg dm-3, respectively. The critical levels, corresponding to the recommended P rate were 13 and 74 mg dm-3 for K in soil (Mehlich-1). The N, P and K levels in the shoot dry matter of physic nut were 37.4, 2.1 and 35.7 g kg-1, respectively.

Dessorção de fósforo por silício em solos cultivados com eucalipto

With the objective to evaluate the desorption of phosphorus by silicon in surface layers of a Dark-Red Latosol (Oxisol) under cerrado vegetation and Cambisol (Inceptisol), under open cerrado vegetation at Campos das Vertentes physiographical region State Minas Gerais, experiments were carried out under greenhouse conditions at the Soil Science Department of the Federal University of Lavras, Minas Gerais state, Brazil, from August 1997 to May 1998. Each soil was submitted to three sequential incubations: (a) CaCO3 + MgCO3 to maintain the pH around 6.0; (b) basic fertilization, including phosphorus in one dose calculated to maintain 0.2 mg L-1 of P in soil solution; and (c) six silicon (CaSiO3) doses defined with basis on phosphorus dose. Seedlings of Eucalyptus grandis were cultivated during 120 days in pots with 3 dm3 of soil. Dry matter production and dry matter P content were evaluated at 60, 90 and 120 days after seedling transplanting to the pots. Response surfaces of these variables were adjusted as a function of Si doses and times. The desorbed P contributed with 15.25% of the content of this nutrient in dry matter of plants cultivated in the Cambisol (higher content of kaolinite).

Produção de mudas de tomateiro em substratos contendo fibra de coco e pó de rocha

ABSTRACT Tomato seedlings production using substrates with coconutfiber and rock waste A greenhouse experiment was carried out to evaluate the ratioof coconut fiber and rock waste, in the tomato seedling production(cultivar Kada Gigante), in Montes Claros, Brazil. The experimentaldesign was of randomized complete blocks with four replicates. Thetreatments were composed of a control and six ratios of coconutfiber (FC) and rock waste (RG): T 1 - Commercial SubstrateHortimix ® ; T 2 - 0% FC + 100% RG; T 3 - 20% FC + 80% RG; T 4 -40% FC + 60% RG; T 5 - 60% FC + 40% RG; T 6 - 80% FC + 20%RG; T 7 - 100% FC + 0% RG. The cultivation was done in polystyrenetrays with cells of 3.5 x 3.5 x 5,0 cm. Stem diameter, seedling height,emergency speed index, emergency percentage, root and aerial partof fresh and dry matter were evaluated. In almost all the evaluatedcharacteristics the commercial substrate was better than the substratescontaining coconut fiber and rock waste. Among the substratescontaining coconut fiber and rock waste, the seedlings with bettercharacteristics were obtained with a mixture of approximately 70%of the volume of coconut fiber.

Organic residue, limestone, gypsum, and phosphorus adsorption by lowland soils

A aplicacao de residuo orgânico e uma alternativa de baixo custo para reduzir a aplicacao de fertilizantes inorgânicos e corretivos. Com objetivo de estudar a relacao da aplicacao de residuo orgânico, calcario e gesso com adsorcao de fosforo em solos de varzea conduziram-se simultaneamente quatro experimentos com os solos Organossolo Mesico (OY), Gleissolo Melânico (GM), Gleissolo Haplico (GX) e Neossolo Fluvico (RU). O delineamento experimental utilizado foi o inteiramente casualizado, em esquema fatorial 3x2, com cinco repeticoes, sendo tres praticas de correcao do solo (calcario, gesso e sem corretivo) e dois niveis de residuo orgânico com e sem esterco de curral curtido. Amostras dos solos foram incubadas por 60 dias com e sem incorporacao do residuo orgânico; apos este periodo, por mais 30 dias com os corretivos e em seguida por 60 dias com o fosforo e uma adubacao basica com macro e micronutrientes. Determinaram-se o fosforo remanescente, capacidade maxima de adsorcao de fosforo, pH, Al trocavel e indice tampao de fosforo. A aplicacao de residuo orgânico, calcario - pela elevacao do pH e reducao dos teores de Al trocavel - e gesso - pela reducao de Al trocavel - reduzem a adsorcao de fosforo nos solos de varzea estudados.

Crescimento de mudas de pinhão-manso em resposta a adubação com superfosfato simples e pó-de-rocha

Research into rock-flour have shown the potential of some of these residues in promoting the mineral enrichment of soils; a practice defined as stonemeal soil. Such practice aims to increase soil fertility and provide good productivity and greater agricultural sustainability. The present study had as objective to evaluate the growth of jatropha seedlings (Jatropha curcas L.) in response to fertilization of the substrate with single superphosphate and rock-flour. The experiment was setup and conducted from September to November, 2007, in a greenhouse at the Institute of Agricultural Sciences/UFMG. The treatments, in a 2 x 5 factorial design of randomized blocks, with three replications, corresponded to two doses of rock-flour (0 and 20 kg m-3 of substrate) and 5 doses of single superphosphate (1.25, 2.5, 5.0, 7.5 and 10.0 kg m-3 of substrate). Plant height, stem diameter, plant height/stem diameter ratio, number of leaves per plant, leaf area, fresh and dry matter of root and shoot, total fresh and dry matter, shoot/root dry-matter ratio, dry matter content and the Dickson quality index- IQD, were all evaluated. The results show no significant interaction between the levels of phosphorus and rock-flour applied and the variables studied. The application of single superphosphate was significant for plant height, stem diameter, leaf area, root, shoot and total fresh matter, with a positive response up to the maximum applied phosphorus dosage.

Production and quality of tomato fruits under organic management

Information about the production and quality of tomato cultivars under organic management and the conditions of climate and soil from the north region of Minas Gerais State, Brasil, are scarce. Thus, this research was carried out to evaluate the production and quality of tomato cultivars under organic management, in this region. The treatments consisted of four open pollination tomato cultivars (Chadwick Cherry, Pitanga vermelha, Santa Clara and Santa Cruz Kada) and five hybrid cultivars (Marguerita, Nicolas, Ellen, Magestade and Dominador). The experimental design was of randomized blocks with three replications. The experiment was carried out using organic fertilization in the initial preparation of the area, compost and rock phosphate and sprays with Bordeaux mixture, neem oil and fertilizer. The marketable yield varied from 12.3 t ha -1 to 23.9 t ha -1 . The hybrid Marguerita presented higher marketable production (23.9 t ha -1 ). The cultivars Chadwick Cherry and Pitanga Vermelha reached similar production as most cultivars and larger proportions of marketable and giant fruits, and therefore, better market quality. All the cultivars presented low potassium and manganese levels in foliar tissue suggesting an evaluation after various organic manuring cycles and better nutrition conditions are necessary to permit the comparison of the performance of cultivars in this system.

Metais pesados e patógenos em milho e feijão caupi consorciados, adubados com lodo de esgoto

The objective of this work was to evaluate the effect of fertilization with sewage sludge submitted to different treatments of sanitization on contamination with heavy metals and pathogens in soil and grains of maize - cowpea intercropping system. The experimental design was completely randomized blocks with three replicates, corresponding to: soil without fertilization; liming and chemical fertilization; sewage sludge; sewage sludge sanitized with nim; sewage sludge sanitized with lime; composted sewage sludge and ipomoea; sewage sludge and ipomoea composted with rock phosphate; sewage sludge with rock phosphate incorporated in the soil; sewage sludge sanitized with nim and rock phosphate incorporated in the soil; sewage sludge sanitized with lime and rock phosphate incorporated in the soil; sewage sludge and ipomoea composted with rock phosphate incorporated in the soil. The pathogen density in the soil was extremely low and there were no differences between treatments. The heavy metal concentrations in the soil, including sewage sludge, did not surpass the maximum limits of annual addition and the permissible maximum limits for soils. In spite of this, the concentrations of Pb in maize grains, and Pb and Cr in cowpea grains, reached values above the limits permitted for agricultural products, independent of the addition of sewage sludge in the soil. In general, no influence of type of sewage sludge in relation to content of heavy metals in grains of corn and cowpea was observed.

Preparo do solo e adubação nitrogenada na produtividade do milho em latossolo sob vegetação de cerrado

The effects of soil preparation systems and doses of nitrogen on total dry matter, straw and grain production and on nitrogen accumulation by corn plants (Zea mays L.) cultivated under irrigation were evaluated in a field experiment in a Dark-Red Latosol (Oxisol), originally under cerrado vegetation, at EMBRAPA/CNPMS experimental station, Sete Lagoas, Minas Gerais State, Brazil, from November, 1995 to June, 1996. The soil preparation systems studied were: no till, conventional till with disk plow and conventional till with moldboard plow. The nitrogen doses were: 0, 60, 120 and 240 kg ha-1 N, applied in cover. The highest productions of dry matter yield and grains and accumulated nitrogen were obtained in the no till system. The plants did not linearly respond to N application, considering the straw and grain production. The greatest efficiency of N utilization by the crop occurred in the no till system, in the 60 kg ha-1 N, as evidenced by the highest recover of applied N.