RESUMO: O uso intensivo de produtos fitossanitários na lavoura de arroz irrigado ( Oryza sativa L.) tem causado preocupação quanto ao impacto ambiental sobre comunidades de organismos aquáticos não alvos que são habitantes naturais nesses agroecossistemas. O objetivo da presente revisão é analisar os dados atualmente existentes na literatura sobre alguns importantes fungicidas e inseticidas (tais como trifloxistrobina, tebuconazol, triciclazol, lambda-cialotrina e tiametoxam), os quais são usados para controlar pragas e doenças na lavoura de arroz irrigado, bem como seus efeitos sobre a comunidade de organismos aquáticos não alvos.

ABSTRACT: The intensive use of plant protection products in rice paddy fields ( Oryza sativa L.) has caused concern about the environmental impact on communities of non-target organisms that are natural inhabitants in these agroecosystems. The purpose of this review is to analyze the data currently available in the literature about some important fungicides and insecticides (such as trifloxystrobin, tebuconazole, tricyclazole, lambda-cyhalothrin, and thiamethoxam), which are currently used to control pests and diseases in rice paddy fields, as well as their effects on the community of non-target aquatic organisms.

ABSTRACT Rice monoculture in lowlands can cause problems for management practices in crop fields, for example, in weed control. For this reason, corn in rotation with irrigated rice in lowlands may be advantageous, despite problems with soil compaction and water excess. The objective of this study was to evaluate soil physical properties and corn performance in soil management systems in an Albaqualf soil (lowlands). Two experiments were conducted in the field, in the 2013/14 and 2014/15 crop seasons. The experimental design was randomized blocks with two factors. There were three levels for the first factor, consisting of soil management practices: soil chiseling 45 days before sowing to a depth of 0.3 m; conventional tillage with two diskings to a depth of 0.1 m and subsequent leveling of the soil; and no-till. The second factor was composed of two levels: sowing on raised seedbeds, and without raised seedbeds. The soil parameters of bulk density, total porosity, macroporosity, microporosity, volumetric moisture, and soil resistance to mechanical penetration (RP) were evaluated. The corn parameters were plant height, shoot dry matter, leaf area, height of the first ear of corn, grains per ear, and grain yield. Soil chiseling resulted in lower RP and higher macroporosity in the 0.1-0.2 and 0.2-0.3 m layers. In raised seedbeds, the 0.00-0.05, 0.05-0.10, and 0.10-0.20 m layers were lower in RP and bulk density. Moreover, higher soil macroporosity was observed in relation to the treatment without raised seedbeds. In general, the highest grain yields were found in the treatments with lower RP and higher macroporosity in the root system region. Increased porosity accelerated water drainage in the soil, reducing the time that soil airspace was filled with water, which is a limiting factor for root development. In Albaqualf soils, planting corn in chiseled soil provides higher corn yields compared to conventional tillage, and planting corn on raised seedbeds provides higher corn yields compared to the lack of raised seedbeds.

Resumo: O objetivo deste trabalho foi avaliar o efeito de sistemas de plantio e irrigação suplementar em faixas sobre o rendimento de grãos de soja, em áreas com presença de camada compactada próxima à superfície do solo. Dois experimentos foram realizados em blocos ao acaso, em faixas, com quatro repetições, no Estado do Rio Grande do Sul. O experimento 1 foi realizado em Santa Maria, correspondente às safras de 2013/2014 e 2014/2015; e o experimento 2, em Formigueiro, na safra 2013/2014. Os tratamentos consistiram dos fatores A e D. O fator A considerou os seguintes sistemas de plantio: A1, semeadura com discos duplos desencontrados; A2, semeadura com disco ondulado de 12 ondas; A3, semeadura com haste sulcadora; A4, semeadura com haste sulcadora e um mecanismo de acomodação do solo; A5, semeadura em microcamalhão; e A6, escarificação do solo e semeadura com disco duplo desencontrado. O fator D consistiu de tratamentos com ou sem irrigação. Na safra 2014/2015, alterou-se o fator A4 por haste desencontrada a 5 cm da linha de semeadura. O experimento 2 constituiu-se apenas do fator A do experimento 1, sem o tratamento microcamalhão. Os sistemas com escarificação do solo e haste sulcadora são os que proporcionam maior rendimento de grãos. A irrigação realizada em condições de umidade do solo abaixo de 60% da capacidade de campo aumenta o rendimento de grãos.

Abstract: The objective of this work was to evaluate the effect of planting systems and supplementary border irrigation on soybean yield in areas of a compacted layer in the soil subsurface. Two experiments were carried out in a randomized complete block design, in a factorial arrangement, with four replicates, in the state of Rio Grande do Sul, Brazil. Experiment 1 was performed in Santa Maria, in the 2013/2014 and 2014/2015 growing seasons; and experiment 2 in Formigueiro, in the 2013/2014 crop season. The treatments consisted of factors A and D. Factor A considered the following planting systems: A1, sowing using double disks; A2, sowing using notched disks; A3, sowing using shanks; A4, sowing using shanks and soil accommodation mechanism; A5, raised bed system; and A6, deep tillage and sowing using double disks. Factor D consisted of irrigated or nonirrigated treatments. In the 2014/2015 growing season, factor A4 was changed using a shank at 5 cm from the seeding line. Experiment 2 consisted only of factor A of experiment 1, without the raised bed system. The systems with deep tillage and sowing using a shank provide higher soybean grain yield. Irrigation at soil moisture conditions lower than 60% of field capacity increases soybean grain yield.