Plantas de cobertura, adubação nitrogenada e produção de sementes de feijoeiro

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Phosphorus utilization by corn as affected by green manure, nitrogen and phosphorus fertilizers

The objective of this work was to evaluate the utilization by corn plants of P from triple superphosphate fertilizer labeled with P-32 (P-32-TSP), and of P from soil as affected by N rates and by the green manures (GM) sunn hemp (Crotalaria juncea) and millet (Pennisetum glaucum). The experiment was carried out using pots filled with 5 kg Oxisol (Rhodic Hapludox). A completely randomized design was used, in a 4x4x2 factorial arrangement, with four replicates. The treatments were: four P rates as TSP (0, 0.175, 0.350, and 0.700 g P per pot); four N rates as urea (0, 0.75, 1.50, and 2.25 g N per pot); and sunn hemp or millet as green manure. The additions of N and P by the GM were taken into account. After grain physiologic maturation, corn dry matter, P contents, accumulated P, and P recovery in the different treatments were measured. P-32-TSP recovery by corn increased with N increasing rates, and decreased with increasing rates of P-32-TSP. The mineral fertilizer provides most of the accumulated P by corn plants. The recovery of P-32-TSP by corn was 13.12% in average. The green manure species influence the assimilation of P-32-TSP by the plants.

Effects of early compost application on no-till organic soybean

Weed control has always been an important issue in agriculture. With the advent of no-till systems, soil erosion was reduced but herbicide use was increased. Organic no-till systems try to adjust reduced erosion to the no use of herbicides. Nevertheless, this adjustment is limited by the cost of mechanical weed control. This cost may be reduced by improved cultural weed control with cover crops mulches. In this paper we report a study on the application of compost manure on an oats winter cover crop, preceding soybean, instead of on the soybean summer crop. Treatments comprised a control without compost manure, and compost manure doses of 4 and 8 Mg ha-1 applied either on oats in winter or soybean in summer, organized in a randomized block design, with five replications. In summer, plots were split into weed-controlled or not controlled subplots. The timing of application and the manure doses did not affect the oats biomass or the soybean performance. However, in summer, without water stress, the application of manure at 8 Mg ha-1 directly on soybean has reduced weed biomass in this crop.

L'inerbimento nell'ecosistema vigneto: confronto di metodologie di misura del consumo idrico del prato e risposta allo sfalcio

Water resources management will become increasingly important in agriculture as global warming takes place. Cover crop is largely used in viticultural areas based on the many positive agronomic and environmental benefits it provides. However, it is not clear what effect the cover crop can have on water use in the vineyard. This study is designed to develop a further understanding of the role cover crops play in total water use in the vineyard and develop our understanding of the potential use of cover crops as a water management tool. Two techniques were used to measure cover crop water use, the mini-lysimeters and a portable open chamber and data from both was compared to reference evapotranspiration (ETo) (FAO guidelines). While the mini-lysimeters seemed to be limited in their ability to accurately represent the water use of the surrounding soil, the open chamber method is a reliable and suitable instrument to be used for the accurate measurement of evapotranspiration. Further, the relationship between vineyard grass water use and the contributing environmental factors thought to influence water use were analyzed. A strong relationship between total available radiation and cover crop evapotranspiration was found suggesting the possibility of an indirect method of evapotranspiration measurement in a vineyard grass cover crop. Mowing the cover crop was determined to significantly effect transpiration as shown by both the mini-lysimeter and open chamber, however, the reduction was largely dependent on the growth rate of the grass.

Oat Variety Trials, 2010 and 2011

Oat is the major spring-sown, small grain crop in Iowa. Spring-sown small grains can be used for grain and straw production, as a companion crop to establish hay and pastures, or as a source of early-season forage as hay or haylage. Because small grains generally mature before the end of July, a forage legume, cover crop, or green manure crop can follow oats, or animal manure can be spread on the field in which oats were grown.

Manejo de suelo mediante coberturas vegetales establecidas

El objetivo de esta investigación fue determinar los efectos de las coberturas vegetales en el microclima de la planta de vid. Se compararon cinco coberturas de diferente ciclo vegetativo con respecto al manejo de suelo sin labranza mediante aplicación de herbicidas. El estudio se desarrolló en un viñedo cv. Malbec conducido en espaldera alta, situado en Agrelo, Luján de Cuyo, Mendoza, Argentina. Se determinaron parámetros microclimáticos, temperatura, humedad relativa y radiación a nivel de racimos, temperatura del suelo, cantidad y calidad de la radiación reflejada por la cobertura. También se midió la expresión vegetativa y de uvas y el potencial enológico. Se verificó una significativa disminución de la radiación fotosintéticamente activa (RFA) reflejada por las coberturas con una menor relación “Rojo/Rojo lejano" comparada con el suelo descubierto. Sin embargo, el efecto no se percibió dentro de la canopia debido a que las coberturas permanentes de trébol rojo (Trifolium pratensis) y agropiro alargado (Agropyron elongatum) restringieron el vigor de las cepas, disminuyendo el crecimiento de brotes y el tamaño de hojas, lo cual se tradujo en una mayor recepción directa de la RFA a nivel de racimos. No hubo una significativa variación en cuanto a temperatura máxima, mínima y amplitud térmica a nivel de racimos. No obstante ello, los tratamientos con mayor cobertura de suelo tendieron a reducir levemente la temperatura mínima a nivel de racimos. La humedad relativa en la canopia no fue significativamente afectada. El trébol rojo, el agropiro alargado, la mezcla centeno-cebadilla (Secale cereale-Bromus catharticus) y el sorgo del Sudán (Sorghum sudanensis) redujeron notablemente la amplitud térmica del suelo. El efecto fue determinado principalmente por la disminución de la temperatura máxima. Las coberturas vegetales con alguna dificultad para desarrollarse durante su ciclo vegetativo tuvieron un comportamiento intermedio o uno muy similar al de un suelo descubierto. La introducción de una cobertura permanente con buena invasión del sitio interfilar permitió modificar indirectamente las características microclimáticas de la canopia, a través del control del crecimiento vegetativo y de los rendimientos de la planta de vid, modificando el equilibrio vigor / producción del viñedo, y por lo tanto la composición de las uvas y del vino elaborado.

Estudio del empleo de cubiertas vegetales temporales para la regulación del régimen hídrico, crecimiento y manejo sostenible del viñedo

RESUMEN El ensayo se llevo a acabo en un viñedo de Syrah durante 8 años y en un viñedo de Merlot durante 3 años. Ambos viñedos regados y situados en Colmenar de Oreja (Madrid) (40º 8’N, 3º 23’W) con clima típicamente Mediterráneo. Siete tratamientos con cubiertas vegetales se han comparado con dos tratamientos con suelo desnudo usados como control. Las cubiertas vegetales fueron seis tratamientos de cereales (Centeno) y un tratamiento de enyerbado autosembrado (Bromus spp) y los tratamientos de suelo desnudo fueron uno manejado con laboreo y otro manejado con herbicida. Los seis tratamientos de centeno se han manejado de seis formas distintas. La primera sembrada todos los años y eliminada en brotación mediante herbicida de post-emergencia. La segunda sembrada todos los años y eliminada un mes después de la brotación mediante siega. La tercera sembrada todos los años y eliminada en floración mediante siega. La cuarta sembrada todos los años y eliminada en brotación mediante herbicida de post-emergencia. La quinta sembrada todos los años y eliminada un mes después de la brotación mediante siega. La sexta sembrada todos los años y eliminada en floración mediante siega. La utilización de cubiertas vegetales ha tenido efectos beneficiosos sobre el contenido en materia orgánica, la compactación y la infiltración del suelo, mejorando las condiciones para el desarrollo de las raíces. Estas mejoras y la escasa competencia de la competencia durante el crecimiento del sistema radical de la vid han producido un incremento del sistema radical en las plantas mantenidos con cubierta vegetal. La competencia de las cubiertas vegetales ha reducido la disponibilidad hídrica de la vid, incrementándose la absorción en zonas con mayor disponibilidad hídrica (como la línea) antes de floración. El mayor desarrollo radical de las vides con cubierta autosembrada ha permitido agotar más intensamente las reservas de agua en el suelo. La competencia de las cubiertas ha reducido en mayor medida el desarrollo vegetativo que el productivo. Lo que ha disminuido, en algunas cubiertas vegetales, el consumo hídrico de la vid, aumentando el potencial hídrico foliar y la fotosíntesis durante la maduración. Sin embargo, el incremento en la fotosíntesis no ha compensado el mayor desarrollo foliar de los tratamientos con suelo desnudo, lo que ha provocado que estos tratamientos presenten la producción de materia seca más elevada. El empleo de cubiertas vegetales ha reducido la producción principalmente limitando el número de bayas por racimo, ya que el aporte de riego ha minimizado los efectos del manejo del suelo sobre el tamaño de baya. La utilización de cubiertas vegetales temporales ha mejorado la iluminación de los racimos, lo que ha producido un aumento de la síntesis de antocianos durante las primeras fases de la maduración, pero un incremento de la degradación de los mismos al final de la maduración. Esto ha provocado que durante la vendimia los tratamientos de suelo desnudo presenten un mayor contenido de antocianos por baya que los tratamientos mantenidos con cubierta temporal. Estos resultados muestran que el efecto del manejo del suelo depende en gran medida de las condiciones del medio, y que sus efectos en climas calidos y secos son muy distintos a los observados en climas frescos y húmedos. ABSTRACT The trial was conducted over a period of 8 years in a Syrah vineyard and over a period of 3 years in a Merlot vineyard. Both vineyards were irrigated and situated near Colmenar de Oreja (Madrid) (40º 8’N, 3º 23’W) a typical Mediterranean climate. Seven Annual cover crops treatments were compared to two bare soil treatments, used as control. Cover crops were six cereals treatments (Rye) and one auto-sowing treatment (Bromus spp) and the treatments of bare soil were one tilled management treatment and another with herbicide treatment. The six Cereal treatments were managed in different manners. First sowing every year and were eliminated in bud breaking with post-emergency herbicide. The second sowing annually and were eliminated one month after bud breaking through harvesting. The third sowing annually and were eliminated in flowering by mowing. The fourth sowing annually and were eliminated with post-emergency herbicide in bud breaking. The fifth sowing annually and were eliminated by mowing one month after bud breaking. . The third sowing annually was eliminated by mowing in flowering. The use of annual cover crop have improved soil organic matter, soil infiltration rate and soil solidity, resulting in a more favourable environment for roots growth. These improvements and low competitive ability during root growing have increases grapevine root density in plant management with cover crop. The Cover crop ability reduced plant available water, increasing root water uptake in the soil with more available water (such us line) before flowering. More growth of grapevine root density with auto-sowed cover crops has allowed using the water under soil more rapidly. The cover crop ability has reduced vegetative growth more than yield. What has been reduced in some vegetative cover crop has been the consumption of water, and increasing the leaf water potential and foliar and photosynthesis during growth activity. Moreover, the increased in photosynthesis activity could not “Compensate” higher leaf growth of treatment of bare soil, where these treatments had resulted in the greatest amount of dry material. The use of cover crops has reduced the crop mainly reducing the fruit set, because the irrigation had reduced the cover crop effect in the berry growth. The use of temporary cover crop increased berry sunlight exposure and skin anthocyanin synthesis during early rippenig, but excessively high temperature increased anthocyanin degradation during last part of ripenning. So, at the vineyard harvest period the treatments with bare soil plant had a more anthocyanin content per grape than the temporary cover crop plant treatments. These results suggest that the effects of soil handling mainly depends on the environmental condition, and their effects in hot and dry climate are so different from the effects in cold and moist climates.

Morphological Functions to Quantify Three-Dimensional Tomograms of Macropore Structure in a Vineyard Soil with Two Different Management Regimes

Soil tomography and morphological functions built over Minkowski functionals were used to describe the impact on pore structure of two soil management practices in a Mediterranean vineyard. Soil structure controls important physical and biological processes in soil–plant–microbial systems. Those processes are dominated by the geometry of soil pore structure, and a correct model of this geometry is critical for understanding them. Soil tomography has been shown to provide rich three-dimensional digital information on soil pore geometry. Recently, mathematical morphological techniques have been proposed as powerful tools to analyze and quantify the geometrical features of porous media. Minkowski functionals and morphological functions built over Minkowski functionals provide computationally efficient means to measure four fundamental geometrical features of three-dimensional geometrical objects, that is, volume, boundary surface, mean boundary surface curvature, and connectivity. We used the threshold and the dilation and erosion of three-dimensional images to generate morphological functions and explore the evolution of Minkowski functionals as the threshold and as the degree of dilation and erosion changes. We analyzed the three-dimensional geometry of soil pore space with X-ray computed tomography (CT) of intact soil columns from a Spanish Mediterranean vineyard by using two different management practices (conventional tillage versus permanent cover crop of resident vegetation). Our results suggested that morphological functions built over Minkowski functionals provide promising tools to characterize soil macropore structure and that the evolution of morphological features with dilation and erosion is more informative as an indicator of structure than moving threshold for both soil managements studied.

Parallel sets and morphological measurements of CT images of soil pore structure in a vineyard

Important physical and biological processes in soil-plant-microbial systems are dominated by the geometry of soil pore space, and a correct model of this geometry is critical for understanding them. We analyze the geometry of soil pore space with the X-ray computed tomography (CT) of intact soil columns. We present here some preliminary results of our investigation on Minkowski functionals of parallel sets to characterize soil structure. We also show how the evolution of Minkowski morphological measurements of parallel sets may help to characterize the influence of conventional tillage and permanent cover crop of resident vegetation on soil structure in a Spanish Mediterranean vineyard.

Effects of soil management in vineyard on soil physical and chemical characteristics

Cover crops in Mediterranean vineyards are scarcely used due to water competition between the cover crop and the grapevine; however, bare soil management through tillage or herbicides tends to have negative effects on the soil over time (organic matter decrease, soil structure and soil fertility degradation, compaction, etc). The objective of this study was to understand how soil management affects soil fertility, compaction and infiltration over time. To this end, two bare soil techniques were compared, tillage (TT) and total herbicide (HT) with two cover crops; annual cereal (CT) and annual grass (AGT), established for 8 years. CT treatment showed the highest organic matter content, having the biggest amount of biomass incorporated into the soil. The annual adventitious vegetation in TT treatment (568 kg dry matter ha-1) that was incorporated into the soil, kept the organic matter content higher than HT levels and close to AGT level, in spite of the greater aboveground annual biomass production of this treatment (3632 kg dry matter ha-1) whereas only its roots were incorporated into the soil. TT presented the highest bulk density under the tractor track lines and a greatest resistance to penetration (at 0.2 m depth). AGT presented bulk density values (upper 0.4 m) lower than TT and penetration resistance in CT lower (at 0.20 m depth) than TT too. Effects of soil management in vineyard on soil physical and chemical characteristics - ResearchGate. Available from: http://www.researchgate.net/publication/268520480_Effects_of_soil_management_in_vineyard_on_soil_physical_and_chemical_characteristics [accessed May 20, 2015].

Destino no ambiente e comportamento agronômico de atrazina em resposta a doses e níveis de palha de espécies de cobertura de solo

The use of cover crops is a fundamental strategy to the weed management in Southern Brazil. In highly infested areas, the herbicides use is increasing, which increases the costs of the crops production as well as the environmental contamination. Oat and velvet bean plants havecontrasting characteristics regarding to residues decomposition speed and the capacity to immobilize Nitrogen in the soil, providing distinct results of weeds suppression throughout the time, and therefore, requiring distinct management strategies before, during, and after the corn crop establishment. The general objective of the experiment was to evaluate the environmental dynamics of the herbicide atrazine, the corn grain yield, and the efficiency of the weed control, considering areas with distinct history regarding the use of mulching, levels of straw and rates of atrazine. For this, the experiment was carried out in two parts: in the first part, two trials with the corn crop were established, one using oat and the other using velvet bean as cover crops. The experimental design used for both field trials was randomized complete blocks arrangement with four replications. The factor A was constituted by four levels of straw (0; 0.75x; 1.5x; 3x) and the factor B was constituted by four rates of the herbicide atrazine (0; 2100; 4200; 8400 g a i. ha-1). Soil samples were collected for greenhouse trialsto determine the persistence. Atrazine leaching evaluation was performed by chromatography using samples collected over the soil profile.In the field, the weed density, the fresh and dry weight and the yield of the corn were evaluated. In the greenhouse trials, the main variables evaluated were plant height and injury caused by the herbicide toxicity. In the second part, soils with distinct covering history were sampled, and the mineralization and sorption studies, both with 14C-atrazine, were conducted in the laboratory. The experimental design was randomized complete blocks arrangement with four replications. The results from the field experiment show that the high levels of straw above ground, isolated, were not efficient to control completely the weeds, and that high levels of velvet bean`s straw decreased the corn potential yield. The greenhouse trials showed that high levels of oat straw prevent the scape of atrazine to soil, this effect of oat straw upon the herbicide availability on soil was detected up to 12 days after spraying. The half-life of atrazine sprayed over oat straw varied from 7 to 14 days after spraying, while the half-life of atrazine sprayed over velvet bean varied from 5 to 14 days after spraying. Increasing oat straw levels presents the capacity to reduce the lixiviation of atrazine in the soil profile, however, this effect was not verified when using velvet bean straw, because the herbicide was not detected in the soil profile, at 21 days after spraying. The chromatographic analysis indicate thatthe atrazine concentrates closer to the soil surface regardless of amount of straw, not being detected deeper than 8 cm in the soil. The accumulated mineralization of 14C-arazine sprayed over V. sativa is superior if compared to soils with S. cereale or non-covered soils. The sorption coefficient of atrazine is superior when sprayed over straw than over the soil.

Adubação de sistemas: antecipação de adubação nitrogenada para a cultura do milho em integração lavoura-pecuária

Traditionally in no-tillage systems, fertilization is done to the catch crop. In general nutrient cycling in crop systems has not been treated as an important tool in the process of nutrient supplying for plants. The type and the condition in which vegetable residuesis decomposed can affect the efficiency of nutrient cycling.This study assessed the effect of anticipated nitrogen fertilization in crop-livestock systems on cultivated cornproduction, rate ofnutrient release from plant residue, and theN-minerallevels of soil. The study was carried out in the city Abelardo Luz (SC) in a Clayey Oxisol. The experimental design was a randomized block design with three replications. The treatments were arranged in a 2 x 2 factorial arrangement. The first factor was N Fertilization Time: in the N-Pasture level, nitrogen (200 kg ha-1 N) and N-Grains level, no nitrogen was applied. The second factor was the Grazing Height, characterized by two sward heights of oat at 15 cm (Low Height Pasture) and at 30 cm (High Height Pasture). Corn hybrid ‘Máximus’ was sowed in 10thOctober, 31 days after the removal of animals. In the twelve resulting plots from the combination of treatments on pasture phase (N Fertilization Time x Grazing Height) rates of N-fertilizer (0, 100, 200 e 300 Kg ha-1 of N) as urea were allocated in the split plot.We conclude that anticipated N fertilization of winter cover crop pasture to provide high-quality forage and carry-over N to the subsequent corn crop and may eventually replace side drees nitrogen fertilization on corn and can improve overall N fertilizer efficiency use in integrated crop-livestock systems.The rate of K release from plant residues is very fast, releasing large quantities in the first days after plant desiccation.Despite of considerably high nitrogen dose used in both the pasture and at the grain crop it was not observed nitrate leaching risks during the study period.

Adubação nitrogenada no milho em sucessão à plantas de cobertura sob sistemas de cultivo do solo

To achieve high yields the corn crop is dependent on nitrogen. Systems of cover crops preceding corn and form of land cultivation are essential for the best use of nitrogen by corn. This study aimed to evaluate the use or not of nitrogen fertilization in corn in succession to cover crops, planted in three cropping systems. The experimental design was randomized blocks with sub-divided portion where the main plots consisted of three cultivation systems (tillage, conventional tillage and minimum tillage), the subplots by four plant cover in monocrop (oat, hairy vetch, field peas and turnip) and sub-subplots by nitrogen fertilization (0 and 160 kg ha-1 N). Evaluations were performed, the cover crops, soil cover rate, dry matter, content and accumulation of nutrients. In corn we evaluated yield components, yield, chlorophyll and nutrient levels in leaves. Among the species coverage studied the oat showed hardiness in the experiment, covering ground faster and showing more dry matter, however vetch hairy showed higher concentrations of N, P and K and higher accumulation of N ha-1. The soil tillage system influenced the K leaf content. The interaction cultivation x coverage showed significance for the total chlorophyll of corn. In the absence of N, N content and chlorophyll were higher where the corn was sown on the pea and hairy vetch. The corn production, despite a higher average in the presence of nitrogen fertilization, did not differ significantly when used the pea and hairy vetch as a cover crop.

A altura de dossel e a adubação nitrogenada da pastagem podem afetar a nutrição nitrogenada do milho, num sistema de integração lavoura pecuária?

We conducted a field experiment near Abelardo Luz, Santa Catarina, from October 2012 to April 2014, to evaluate the effect interaction of nitrogen fertilization and height of canopy over the N nutrition of corn subsequently grown to pasture. The data belonging to this thesis are related to the first two production cycles obtained in sorghum pasture (2012/2013), oat (2013) and corn crop (2013/2014). In the evaluation of forage sorghum and oat it was used the same experimental design, consisting of randomized complete block in a factorial arrangement (2 x 2) with three replications. The first factor was considered canopy height (Low and High) and the second factor was the fertilization of cover crop pasture (0 and 200 kg N.ha-1). In phase I and II, the combination of factors evaluators were prepared in the same experimental unit. For corn crop the design was a randomized complete block in a factorial design (2X2X4X6) with three replications. Factors considered in corn were: canopy height of pasture (Low and High), nitrogen application times (NG - nitrogen in the grains and NP - nitrogen in pasture), nitrogen fertilization in corn (0, 100, 200 and 300 kg N.ha-1) and time (46, 53, 60, 67, 76 and 103 days after sowing the maize). In phases I and II, in general the use of N in the pasture increased the productive potential of the pasture and animal management and canopy height has changed the dynamics of structural components and botanical pasture. In cold conditions for long periods and not acclimatized plants the adoption of high nitrogen fertilization and height high grazing pasture leave vulnerable to damage caused by the freezing of plants. The anticipation of nitrogen fertilization on pasture positively affects the corn crop by increasing the accumulated dry matter and N content in the plant. Nitrogen nutritional content of corn with the anticipation of fertilization in pasture is suitable for obtaining high crop production in integrated crop-livestock system. When used nitrogen only coverage in corn sufficiency level in the nitrogen nutrition is achieved with the use of 100 kg N.ha-1. With the use of 200 kg N ha -1 NG and NP no difference in nitrogen content and nitrogen nutrition index.

Agriculture, Environmental Incentive Payments, and Water Quality in the Chesapeake Bay

Nonpoint sources (NPS) pollution from agriculture is the leading source of water quality impairment in U.S. rivers and streams, and a major contributor to lakes, wetlands, estuaries and coastal waters (U.S. EPA 2016). Using data from a survey of farmers in Maryland, this dissertation examines the effects of a cost sharing policy designed to encourage adoption of conservation practices that reduce NPS pollution in the Chesapeake Bay watershed. This watershed is the site of the largest Total Maximum Daily Load (TMDL) implemented to date, making it an important setting in the U.S. for water quality policy. I study two main questions related to the reduction of NPS pollution from agriculture. First, I examine the issue of additionality of cost sharing payments by estimating the direct effect of cover crop cost sharing on the acres of cover crops, and the indirect effect of cover crop cost sharing on the acres of two other practices: conservation tillage and contour/strip cropping. A two-stage simultaneous equation approach is used to correct for voluntary self-selection into cost sharing programs and account for substitution effects among conservation practices. Quasi-random Halton sequences are employed to solve the system of equations for conservation practice acreage and to minimize the computational burden involved. By considering patterns of agronomic complementarity or substitution among conservation practices (Blum et al., 1997; USDA SARE, 2012), this analysis estimates water quality impacts of the crowding-in or crowding-out of private investment in conservation due to public incentive payments. Second, I connect the econometric behavioral results with model parameters from the EPA’s Chesapeake Bay Program to conduct a policy simulation on water quality effects. I expand the econometric model to also consider the potential loss of vegetative cover due to cropland incentive payments, or slippage (Lichtenberg and Smith-Ramirez, 2011). Econometric results are linked with the Chesapeake Bay Program watershed model to estimate the change in abatement levels and costs for nitrogen, phosphorus and sediment under various behavioral scenarios. Finally, I use inverse sampling weights to derive statewide abatement quantities and costs for each of these pollutants, comparing these with TMDL targets for agriculture in Maryland.