ABSTRACT: Crop coefficient (Kc) is the ratio between crop evapotranspiration (ETc) and reference evapotranspiration (ETo), representing the phenological effects on crop water consumption. Kc is fundamental to estimating ETc by agrometeorological methods. This research study aimed to determine Kc and ETc values for Guinea grass (Megathyrsus maximus cv. Mombaça) and Bermuda grass (Cynodon spp.), both single cropped for one year and overseeded with black oat (Avena strigosa) and ryegrass (Lolium multiflorum) during fall/winter. The experiment in the field comprised four plots, two for each tropical forage, with and without overseeding. At the center of each plot, there was a weighing lysimeter with an automated system for data collection. ETc was measured daily over four seasons following the lysimetric method; ETo was calculated using the Penman-Monteith equation. ETc and ETo values were used to estimate Kc values. The single cropped Guinea grass showed the highest values for ETc, with mean ETc and Kc of 3.99 mm d–1 and 1.07, respectively. The single cropped Bermuda grass showed ETc and Kc values of 3.57 mm d–1 and 0.96, respectively. The results of paired t-testing for Kc showed no significant differences (p = 0.05) between single cropped and intercropped for both Guinea grass and Cynodon spp. During winter, intercropped Guinea grass did not show an ETc significantly higher than single cropped Guinea grass, with mean Kc values 0.98 for intercropped and 1.10 for single cropped. Similarly, Bermuda grass did not show significant differences between mean Kc values for intercropped (1.02) and single cropped (1.00).

O objetivo deste trabalho foi desenvolver e validar modelos de regressão linear para a estimativa de produção de matéria seca de capim‑tanzânia (Megathyrsus maximus, cultivar Tanzania) em função de variáveis agrometeorológicas. Para tanto, dados de períodos de crescimento da forragem entre 2000 e 2005, em condições de sequeiro em São Carlos, SP, foram correlacionados aos seguintes parâmetros climáticos: temperaturas mínima e média, graus‑dia, evapotranspiração potencial e atual. Foram realizadas regressões lineares simples entre as variáveis agrometeorológicas (independentes) e a taxa média de acúmulo (dependente). As estimativas foram validadas com dados independentes obtidos em São Carlos e Piracicaba, SP. Os melhores resultados estatísticos observados no desenvolvimento e na validação dos modelos foram obtidos para parâmetros agrometeorológicos que levem em consideração o efeito térmico e hídrico conjuntamente, como evapotranspiração real, acúmulo de graus‑dia corrigido pela disponibilidade hídrica e índice climático de crescimento, baseado na temperatura média, na radiação solar e na disponibilidade hídrica. Essas variáveis podem ser utilizadas em simulações e modelos para prever a produção do capim‑tanzânia.

The objective of this work was to develop and validate linear regression models to estimate the production of dry matter by Tanzania grass (Megathyrsus maximus, cultivar Tanzania) as a function of agrometeorological variables. For this purpose, data on the growth of this forage grass from 2000 to 2005, under dry‑field conditions in São Carlos, SP, Brazil, were correlated to the following climatic parameters: minimum and mean temperatures, degree‑days, and potential and actual evapotranspiration. Simple linear regressions were performed between agrometeorological variables (independent) and the dry matter accumulation rate (dependent). The estimates were validated with independent data obtained in São Carlos and Piracicaba, SP, Brazil. The best statistical results in the development and validation of the models were obtained with the agrometeorological parameters that consider thermal and water availability effects together, such as actual evapotranspiration, accumulation of degree‑days corrected by water availability, and the climatic growth index, based on average temperature, solar radiation, and water availability. These variables can be used in simulations and models to predict the production of Tanzania grass.

Climatic risk zoning allows the identification of areas of low risk of reduced crop productivity due to climatic events. In Brazil, losses to agriculture due to climate are mainly caused by drought. The objective of this research was to determine areas of low climatic risk for corn and palisade grass cultivated in integrated crop-livestock systems in Sao Paulo state. Corn varieties characterized by a 120-day growing cycle and soil with three different water holding capacities (sandy, medium and clayey soils) were considered. A daily water balance model was used to simulate planting dates between September and December. The water requirement satisfaction index (WRSI) was calculated for critical phenological phases of both cultures (germination, emergence and tillering of palisade grass and flowering and grain filling of corn). The WRSI values, calculated for a minimum frequency of 80%, were located spatially using the SPRING v. 5.1 geographic information system and the most favorable periods for sowing in different areas were determined. The results showed that there are areas of low climatic risk for cultivation of corn and palisade grass in integrated crop-livestock production systems in Sao Paulo state. Although climatic risk in these areas also depends on soil type, the most favorable period for planting is between October and November.

The objective of this work was to evaluate yield traits and development of palisadegrass under the influence of water deficit during the establishment period. The experiment was carried out in a greenhouse, in a completely random block statistical design in a factorial arrangement and additional treatment (3 × 3 + 1). The treatments referred to the suppression of irrigation at different phases of the establishment (sowing, germination and initial tillerring) until the soil presented water content of 75%, 50%, and 25% of the moisture related to field capacity (qFC), besides control treatment with no water restriction. Evaluations of number of grown tillers per vase, green leaves per tiller and plant height were carried out weekly, for five weeks after the first tillers appeared. Biomass sampling was carried out approximately 30 days after the end of the last applied treatment, when the soil was kept close to 100% of field capacity relative moisture. Tillering and biomass yield of palisadegrass during establishment phase are reduced when water deficit is sufficient to make soil content water reach 25% of relative moisture field capacity, regardless to the season when water shortage takes place.

The objective of this work was to define critical periods for sorghum and palisadegrass cultivated on crop-livestock integrated systems under water deficit. An experiment was carried out in a completely random block design with four treatments (control and interruption of water supply in three periods) and three replicates. Water supply was interrupted until soil water humidity was close to permanent wilting point at the phases: germination of palisadegrass seeds; start of tillering of palisadegrass and initiation of panicles of shorghum; start of shorghum flowering. Water deficit starting at palisadegrass germination delayed intital development of the plants because of the reduction in tillering. Water restriction at panicle initiation phase and at sorghum flowering determined reduction of grain production. Critical periods for intercrop of sorghum and palisadegrass correspond to palisadegrass germination phase and flowering and panicle inititation phase of sorghum.

The objective of this work was to evaluate the development and productive traits of palisadegrass single cultivated or intercropped with corn, in addition to corn intercropped with pasture, under water deficit at different development stages of the plants. It was used a complete block experimental design with split plots and three replicates. Periods of water deficit were placed in the plots and types of cultivation were placed in the subplots. Irrigation was stopped at germination and initial tillering of palisadegrass and at V4 and V15 stages of corn and returned when soil moisture was 40% of available water capacity. Tiller density and palisadegrass height were evaluated weekly. Dry matter (DM) of fractions of herbage mass as well as leaf area of the plants were evaluated at corn tasseling and when grains reached physiological maturity. Components of corn production were determined in the second sampling. In palisadegrass, water influenced only tillering, which was reduced in the plots in which water defict was forced at the moment of germination or at the beginning of tilering, in both cultivation systems. Plant height and DM production were affected only by cultivation, reducing when intercropped with corn. Evaluated production components did not influence corn grain productivity, which was similar in all treatments (average of 10,145 kg/ha). Palisadegrass plants produce more DM in single cultivation than intercropped with corn. Water deficit during germination and initial tillering reduces tillering of palisadegrass during establishment phase. Water deficit, applied in this trial, does not reduce DM yield in palisadegrass or corn.

O objetivo deste estudo foi, a partir da análise e melhoria do processo, fortalecer o processo de "Avaliação dos impactos econômicos, sociais e ambientais de tecnologias da Embrapa Pecuária Sudeste". Utilizou-se uma metodologia baseada no ciclo PDCA, que possibilitou a indicação do ponto-chave (inventário das tecnologias), do fator crítico de sucesso (seleção das tecnologias adotadas), do principal problema (não avaliação das tecnologias), e das principais causas do problema. Com a implantação das ações de melhoria, detectaram-se as vantagens do uso da metodologia, que são: a disponibilização de informações aos executores do processo, para facilitar a realização do trabalho com qualidade, uma vez que foram claramente definidos nesta análise o objetivo, os clientes, os indicadores de desempenho, os produtos e os resultados esperados. Verificou-se a importância da organização e disponibilização de banco de dados com informações sobre as demandas, resultados de pesquisa, e estágio de desenvolvimento de tecnologias. Os clientes internos foram sensibilizados para a necessidade do processo. Demonstrou-se que o processo também é ferramenta útil para a gerência de P&D, para acompanhar passo a passo as quatro fases de: 1) levantamento de demandas; 2) elaboração e execução de projetos; 3) difusão, transferência e inovação; e 4) avaliação de impactos. Verificaram-se várias descontinuidades no processo gerência de P&D. A Análise e Melhoria de Processos - AMP pode ser assimilada e posta em prática por instituições de pesquisa pública, e deve ser estimulada constantemente para ser assimilada e praticada.

The main objective of this study was to use the business process management methodology to strengthen the process of "Economic, social, and environmental impact assessment of technologies from Embrapa Pecuária Sudeste". A methodology based on the PDCA cycle was used, which allowed the indication of the key point (inventory of technology), the critical success factor (selection of the adopted technologies), the main problem (non-assessment of technology), and major causes of the problem. The advantages obtained with the implementation of the BPM are: providing information to process managers and quality work since this analysis clearly defined the objective, customers, performance indicators, products, and expected results. The importance of an organized and available database that provides information on demands, research results, and the development stage of technologies was verified. Internal clients were made aware of the process importance. The process also proved a useful tool for the R&D management stages: 1) demand establishment, 2) development and implementation of projects, 3) dissemination, transfer, and innovation, and 4) impact assessment. There are several discontinuities in the management of R & D. The BPM can be assimilated and implemented by public research institutions and its use should be constantly encouraged.

Reconhece-se cada vez mais a crescente falta de água para irrigação e outros usos. Também, está-se consciente de que, por sua irregular disponibilidade, a qual varia marcadamente ao longo do ano, de ano a ano e de região a região, o uso da água de forma contínua e indefinida, torna-se impossível. Portanto, uma das metas estratégicas para a preservação da disponibilidade e da qualidade dos recursos hídricos consiste em se estabelecer critérios de uso adequado em todas as atividades produtivas, razão pela qual este trabalho aborda a escassez de água, a agricultura irrigada e o meio ambiente, com base em informações e estudos que possam contribuir para o direcionamento de uma agricultura planejada, conservando e otimizando os recursos naturais. Os modelos tecnológicos propostos devem considerar um rigoroso equilíbrio entre produção agrícola e preservação dos recursos naturais. O desenvolvimento atual da irrigação depende de procedimentos tecnológicos e econômicos para otimizar o uso da água, melhorar a eficiência de aplicação, proporcionar ganhos de produtividade baseados na resposta da cultura à aplicação de água e outros insumos, sem que comprometa a disponibilidade e a qualidade do recurso.

There is a growing concern all over the world over the increasing lack of water resources for irrigation and other uses. The irregular availability of water, both in time and space, also greatly affects its use on a continuous basis. One of the strategies for preserving the quantity and quality of water resources consists in establishing criteria for the appropriate use in all productive activities. The objective of this paper is to provide an in-depth analysis on the relationship among water scarcity, irrigated agriculture and the environment, at the same time contributing to studies that may lead to a planned agriculture, preserving and optimizing the natural resources. Modern technological models must consider a rigorous equilibrium involving agricultural production and preservation of natural resources. Today, the development of irrigation depends on technological and economic procedures for water use optimization, improving application efficiency and providing yield gains from crop response to water application and other productive resources, without, however, compromising availability and quality of resources.

Foi avaliado o efeito do nitrogênio na cultura do milho através da fertirrigação, utilizando um sistema de irrigação por aspersão em linha e uréia como fonte de N. O sistema de aspersão em linha foi constituído por 3 linhas com cinco aspersores cada uma, cujo espaçamento foi de 6 metros entre si e 12 metros entre as linhas. O fertilizante foi aplicado nas linhas externas e a linha central aplicou apenas água. A lâmina de água total aplicada durante o ciclo foi de 650 mm. Essa aplicação foi feita de forma uniforme, e as doses de nitrogênio foram decrescentes na direção perpendicular às linhas externas de aspersores, variando de 353 a 30 kg/ha de N. Os resultados obtidos mostraram que as diferentes dosagens de nitrogênio afetaram os seguintes parâmetros medidos: altura das plantas, altura de inserção das espigas, produtividade, comprimento das espigas, peso de mil grãos e teor de nitrogênio nos grãos. O ponto de máxima produtividade de grãos (7634 kg/ha) foi estimado através de uma função de produção da cultura em relação ao fator doses de nitrogênio. A máxima produtividade estimada pode ser atingida com uma dose de 262,6 kg/ha de N.

The nitrogen effect on a corn crop, applied by fertigation through a line source sprinkler system was evaluated, using urea [CO(NH2)2] as nitrogen source. The line source sprinkler system had three pipelines with five sprinklers each. The sprinkler spacing was six meters, and the lateral spacing, twelve meters. Fertigation and irrigaiton were made by the external lines, and the central line was used only for irrigation. The total water depth applied during the crop cicle was 650 mm. This water application was made in an uniform way along the experimental area, and nitrogen levels decreased along the perpendicular direction to the central sprinkler line, ranging from 353 to 30 kg N/ha. Results showed that different nitrogen levels affected the following crop production factors: plant height, corn cob inserction height, corn yield, corn cob length, thousand grain weight, and nitrogen contain of grains. The point of maximum grain yield (7634 kg/ha) was estimated by a crop production function in relation to nitrogen levels. The maximum grain yield was obtained with 262.6 kg N/ha.