ABSTRACT: Sugarcane (saccharum spp.) in Brazil is managed on the basis of “production environments”. These “production environments” are used for many purposes, such as variety allocation, application of fertilizers and definition of the planting and harvesting periods. A quality classification is essential to ensure high economic returns. However, the classification is carried out by few and, most of the time, non-representative soil samples, showing unreal local conditions of soil spatial variability and resulting in classifications that are imprecise. One of the important tools in the precision agriculture technological package is the apparent electrical conductivity (ECa) sensors that can quickly map soil spatial variability with high-resolution and at low-cost. The aim of the present work was to show that soil ECa maps are able to assist classification of the “production environments” in sugarcane fields and rapidly and accurately reflect the yield potential. Two sugarcane fields (35 and 100 ha) were mapped with an electromagnetic induction sensor to measure soil ECa and were sampled by a dense sampling grid. The results showed that the ECa technique was able to reflect mainly the spatial variability of the clay content, evidencing regions with different yield potentials, guiding soil sampling to soil classification that is both more secure and more accurate. Furthermore, ECa allowed for more precise classification, where new “production environments”, different from those previously defined by the traditional sampling methods, were revealed. Thus, sugarcane growers will be able to allocate suitable varieties and fertilize their agricultural fields in a coherent way with higher quality, guaranteeing greater sustainability and economic return on their production.

ABSTRACT: The use of mineral phosphate fertilizers associated with organic residues can improve fertilizer use efficiency and consequently decrease their usage costs. Soil application of filter cake (FC) can provide nutrients and enhance physical quality. This study aimed to evaluate the effects of different phosphate fertilizers [rock phosphate (RP) and triple superphosphate (TSP)] applied at different rates (90 and 180 kg ha-1 P2O5) associated with filter cake (10 Mg ha-1 dry matter) on the soil phosphorus (P) fractions after two consecutive seasons of sugarcane in two distinct soils, sandy and clayey. Yield was significantly improved with FC addition in the first year in both soils, while inorganic P sources did not influence crop yield at either location and in both years. Organic and residual P forms were only slightly altered in the sandy soil. The most significant changes occurred in the labile and moderately labile P fractions in both soils. Filter cake was an effective source of nutrients for plant development, increasing the levels of soil available P and keeping it at agronomically adequate levels for up to two years, however it was not able to facilitate the P release from mineral fertilizers, irrespective of the source or rate.

ABSTRACT The aim of this study was to verify the influence of planting distance and the population of plants, phenological components, and productivity in different maize genetic material. The experiment was conducted during the 2003/04 agricultural year in the city of Jaú/SP, located at latitude 22° 17'S, longitude 48° 34' W and altitude 680 m. Average Were studied, planting distances of 0.45 m and 0.90 m, three densities 50, 75 and 100 000 plants ha-1, and four genetic materials: simple hybrid DKB 333C, triple hybrid DKB 466, AG 2060 and double hybrid the variety AL 2x3x4 factorial scheme Bandeirantes in with 4 replications in randomized blocks. The reduction in the planting row spacing and increasing plant population significantly influenced the percentage of lodged plants and broken corn. Line spacing of 0.45 m, population of 75,000 plants ha-1 and single hybrid material showed the highest productivity of grains with an average of 9077 kg ha-1. Significant interactions were observed line spacing factors versus population of plants and plant population versus materials for grain productivity factor. Phonological components of production: spike length, shank diameter and the diameter of the cobs were influenced by increased plant population ha-1. The experiment was conducted during the agricultural year of2003/04 in the city of Jaú/SP, located at latitude 22° 17'S and longitude 48° 34' Wand an average altitude of 680 m. Were tested, two spacing 0.45 m and 0.90 m, three densities 50, 75 and 100 thousand plants ha-1, and four genetic materials simple hybrid DKB 333C, triple hybrid DKB 466, double hybrid and variety AG 2060 in AL Bandeirantes® factorial design 2x3x4 with 4 replications in randomized blocks.

RESUMEN El objetivo del estudio fue verificar la influencia de la distancia de plantación y de la población de plantas, en los compo nentes fenológicos y en la productividad de diferentes materiales genéticos de maíz. El experimento fue conducido en el municipio de Jaú/SP, localizado en la latitud 22° 17' S, longitud 48° 34' W y altitud media de 680 msnm. Fueron estudiadas dos distancias de plantación: 0,45 m y 0,90 m, tres densidades poblacionales 50, 75 y 100 mil plantas ha-1, y cuatro materia les genéticos: híbrido simple DKB 333C, híbrido triple DKB 466, híbrido doble AG 2060 y la variedad AL Bandeirantes® en esquema factorial 2x3x4 con cuatro repeticiones en bloques al azar. La reducción en la distancia entre líneas de plantío y el aumento de la población de plantas influenciaron significativamente en el porcentaje de plantas acamadas y quebradas del maíz. Espacio entre líneas de 0,45 m, población de 75.000 plantas ha-1 y material híbrido simple presentaron la mayor productividad de granos con promedio de 9.077 kg ha-1. Se observaron interacciones significativas de los factores distancia entre líneas versus población de plantas, y población de plantas versus materiales para el factor productividad de granos. Los componentes fenológicos de producción: largo de la mazorca, diámetro de la mazorca y diámetro de la tusa (marlo) fueron influenciados por el aumento de población de plantas ha-1.

Este trabalho foi realizado com o objetivo de avaliar o potencial produtivo de diferentes variedades de cana-de-açúcar irrigadas plenamente por gotejamento durante dois ciclos. O experimento foi instalado na região de Jaú, SP, em um Latossolo Vermelho eutrófico. O delineamento experimental foi o de blocos casualizados em arranjo fatorial 8 x 2 (variedades x ciclos), com seis repetições. Em cada ciclo foram avaliadas variáveis de qualidade do caldo, produtividade de açúcar e de colmos e eficiência de utilização de água em relação à produtividade de colmos. Observou-se que variedades de cana-de-açúcar respondem diferentemente à irrigação plena, sendo esta resposta influenciada pelas condições climáticas do ano agrícola. Nesta pesquisa apenas o primeiro ciclo de avaliação (cana-planta) foi determinante para diferenciar o desempenho entre as variedades. As variedades IAC91-1099, IACSP96-3060, RB855536, RB867515 e SP85-1115 apresentaram melhor potencial produtivo agroindustrial e menor consumo relativo de água podendo, então, ser recomendadas para o manejo de produção com irrigação por gotejamento.

This study aimed to evaluate the yield potential of different varieties of sugarcane under drip irrigation in two growth cycles. A trial was set up in October 2006 at Jaú region (São Paulo state, Brazil), in an experimental field with a eutrophic Ultisol. The experiment was conducted in randomized complete blocks with factorial treatment structure 8 x 2, constituted by eight sugarcane varieties and two crop cycles, with six replicates. Stalk productivity (TCH), sugar productivity (TPH), juice quality traits and water use efficiency in relation to stalk productivity were evaluated in each crop cycle. It was observed that varieties of sugarcane respond differently to full irrigation, and this response is influenced by climatic conditions of the agricultural year. In this study, only the first evaluation cycle (plant cane) was decisive to differentiate the performance among the varieties. The varieties IAC91-1099, IACSP96-3060, RB855536, RB867515 and SP85-1115 showed higher agro-industrial yield potential and less consumption of water and can be recommended for the management of production under drip irrigation.