Weed Management in Sprinkler-Irrigated Rice: Experiences from Southern Brazil

Sprinkler rice saves water compared to paddy rice. However, in paddy fields, the water table is efficient for weed suppression. In sprinkler rice, there is no water table on soil; thus, weed management used in paddy rice may not be suitable for sprinkler rice, since herbicides and water table are expected to interact. Weed pressure in sprinkler rice is higher than in paddy rice; annual grasses are the main weeds in both paddy and sprinkler rice. Barnyardgrass, goosegrass, crabgrass and Alexandergrass show vigorous growth in sprinkler rice. A 3-year study shows that weeds in sprinkler rice reduce grain yield between 11 and 95%. Herbicides used in conventional and Clearfield® rice (clomazone, imazethapyr + imazapic, imazapyr + imazapic, pendimethalin and penoxsulam) were tested, contrasting paddy and sprinkler rice. Additionally, the technique locally called “needle-point” (glyphosate applied over the first-day emerging rice) was combined with pre- and postemergence herbicides. When using only pre- or postemergence, weeds reduced rice grain yield; a combination of products was the best option for sprinkler-irrigated rice. The Clearfield technology was efficient in controlling most weeds. However, using it combined to the needle-point promoted the best results. The main approaches for weed management in sprinkler-irrigated rice were summarized

Fungicide and insecticide residues in rice grains

ABSTRACT. The objective of this study was to analyse residues of fungicides and insecticides in rice grains that were subjected to different forms of processing. Field work was conducted during three crop seasons, and fungicides and insecticides were applied at different crop growth stages on the aerial portion of the rice plants. Azoxystrobin, difenoconazole, propiconazole, tebuconazole, and trifloxystrobin fungicides were sprayed only once at the R2 growth stage or twice at the R2 and R4 growth stages; cypermethrin, lambda-cyhalothrin, permethrin, and thiamethoxam insecticides were sprayed at the R2 growth stage; and permethrin was sprayed at 5-day intervals from the R4 growth stage up to one day prior to harvest. Pesticide residues were analysed in uncooked, cooked, parboiled, polished and brown rice grains as well as rice hulls during the three crop seasons, for a total of 1,458 samples. The samples were analysed by gas chromatography with electron capture detection (GC-ECD) using modified QuEChERS as the extraction method. No fungicide or insecticide residues were detected in rice grain samples; however, azoxystrobin and cypermethrin residues were detected in rice hull samples

Soil management and application of agricultural gypsum in a Planosol for soybean cultivation

<div><p>ABSTRACT: This study investigated the effects of soil management systems, tillage, and application of gypsum agricultural to soil, on soybean development in lowland areas. The experiment was carried out on an Alfisol in a randomized complete block design in a factorial arrangement. The two soil tillage practices were without deep tillage and with deep tillage. Gypsum treatments were no gypsum application, 500kg of gypsum ha-1, 1000kg of gypsum ha-1, and 1500kg of gypsum ha-1. Deep tillage resulted in less soil resistance to root penetration during ryegrass cultivation during the soybean offseason, 11 months after applying the management treatments, resulting in higher dry mass of ryegrass in the offseason and higher soybean yield in the following year.</p></div

Physical Properties and Crop Management for Corn in an Albaqualf

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

Manejo do azevém no estabelecimento inicial de plantas, na ciclagem de nutrientes e no rendimento de grãos do arroz irrigado

RESUMO: O objetivo deste trabalho foi avaliar o efeito de diferentes manejos da cultura do azevém na entressafra do arroz irrigado, sobre o estabelecimento inicial de plantas, a ciclagem de nutrientes e o rendimento de grãos de arroz. O experimento foi conduzido em área de várzea sistematizada durante os anos agrícolas de 2010/11 e 2011/12, sob delineamento de blocos ao acaso, com cinco repetições com os tratamentos constituídos por: épocas de dessecação do azevém, antecedendo a semeadura do arroz, pousio e retirada da palha através da produção de feno de azevém. Há redução do estande inicial de plantas de arroz irrigado à medida que a dessecação do azevém se aproxima da semeadura do arroz. A utilização do azevém em áreas de várzea intensifica a ciclagem de nutrientes, mas recomenda-se que, em azevém não pastejado, a dessecação seja realizada com antecedência de 60 dias antes da semeadura do arroz irrigado para não prejudicar o rendimento de grãos do mesmo. A produção de feno de azevém é uma alternativa viável para a entressafra em áreas de várzea, pois não prejudica o estabelecimento inicial de plantas de arroz irrigado