Renato Beppler Spohr

Physical quality of irrigated soils in some regions of Central Brazil.

Intensive soil cultivation using heavy machinery, especially when soil moisture content is relatively high, has caused degradation of the physical properties of soil, mainly soil compaction. The objective of this study was to evaluate the physical quality of soil of some irrigated regions of Brazil and to collect information necessary to guide soil management decisions. This study was carried out in areas irrigated by center pivots in the States of Goias, Minas Gerais and Sao Paulo. The soil profile was divided into three soil layers: superficial, intermediate and inferior. The following determinations were conducted: soil texture, bulk density, particle density and soil porosity. Soil types were grouped according to clay content. For each group of clay content, critical values of bulk density and soil macroporosity were established above which (bulk density) and below which (macroporosity) the soil sample were characterized as compacted. Considering the entire area sampled in the superficial layer, 14.2% of the samples collected in Goias, 9.5% of soil samples collected in Minas Gerais and 34% of the samples collected in Sao Paulo presented indications of soil compaction as a function of bulk density and macroporosity.

Production of maize and sorghum for silage in succession to the upland rice

The objective of this work was to evaluate different sowing dates to maximize double-cropping (upland rice followed by either maize or sorghum) and evaluate the economica practicability of this production system in the region of Santa Maria, in the State of Rio Grande do Sul. Two experiments were conducted in the experimental field of the Agricultural Engineering Department of the Federal University of Santa Maria - RS, Brazil, during the 2001/2002 growing season. A randomized block design was used with four replications. Treatments of the first experiment were constituted of four sowing dates of upland rice: September 18, October 4, October 19 and November 5. The treatments of the second experiment were constituted of four sowing dates of maize and sorghum (after the harvest of the upland rice): January 28, February 8, February 20 and March 5. The upland rice sowing dates caused differences in grain yield and the maximum technical efficiency (5.80 Mg ha-1) was observed for the rice sown on October 13. The use of double-cropping cultivation in the southern half of Rio Grande do Sul the State upland rice followed by sorghum for the production of silage, for maximum retnans, the upland rice should be sown during de second half of September.

Danos físicos em estufas plásticas causados pelo vento em Santa Maria, RS

Foram observados danos fisicos causados por rajadas de vento ocorridos na madrugada do dia 19/05/97 no plastico das estufas localizadas no Campus da Universidade Federal de Santa Maria. Os valores de intensidade e direcao das rajadas maximas do vento foram registradas em um anemografo universal tipo IH 1023 a 10m de altura, instalado a aproximadamente 100m ao sul das estufas. Os danos ocorreram quando a velocidade das rajadas maximas ultrapassou 20m s-1 (72km h-1)