Revista Científica Agropecuaria (2000)

© Facultad Ciencias Agropecuarias - UNER

Summary

 Abstracts - No. 4 (2000) ISSN 0329-3602

Revista Científica Agropecuaria 4: 3-11 (2000)

ECONOMIC AND ENVIRONMENTAL BENEFITS OF THE USE OF SURFACE WATER FOR RICE CROP IRRIGATION

Oscar Duarte, Eduardo L. Díaz, Jorge A. Cerana, Marcelo G. Wilson, Ricardo Valenti y René A. Benavídez

Cátedras de Edafología y de Tecnología de Tierras y Aguas I. Facultad de Ciencias Agropecuarias. Universidad Nacional de Entre Ríos. C.C. Nº 24. 3100 Paraná, Entre Ríos. Argentina

Summary: This paper presents the results obtained after applying a mathematical model that simulates the operation of a well and surface reservoir (through damming up) system that irrigates a rice cultivation in the Province of Entre Ríos, Argentina. The development and expansion of the region devoted to rice cultivation is limited to the existence of high-yield reservoirs. In addition, the cost of the fuel necessary for pumping underground water has increased in the last years. It is therefore relevant to consider the use of surface water retained through small dams built with soil from the same area and with machinery owned by farmers. This paper shows the mathematic simulation carried out for the last 21 years. Records of daily rainfalls have been kept in order to assess the amounts saved in fuel by irrigating crops with mini-dams. As a conclusion, the alternative of combining the use of dams and wells produces better economic results as it doubles the irrigated surface. Finally, the downstream effects of dam building are evaluated. In the case of the model applied, only an average 10.7 % of the runoff is retained during irrigation.

Key words: rice irrigation - surface water - mathematical simulation model

4 Table, 5 Figures, 10 References

 Abstracts - No. 4 (2000) ISSN 0329-3602

Revista Científica Agropecuaria 4: 13-18 (2000)

HEIGHT GROWTH RATE AND ITS IMPORTANCE TO ESTABLISH MOWING FREQUENCY IN LAWNS WITH SPORTING PURPOSES

María I. Laurencena, María S. Carponi, Claudia M. A. Scorciapino, Patricia D. Reinoso y Marina L. Butus

Cátedras de Espacios Verdes, Botánica Sistemática y Estadística. Facultad de Ciencias Agropecuarias. Universidad Nacional de Entre Ríos. C.C. Nº 24. 3100 Paraná, Entre Ríos. Argentina

Summary: The height growth rate of a mixture seeds, mainly of Cynodon dactylon L. and Lolium multiflorum Lam. overseeding was estimated at a pre-established mowing frequency of seven days, under different conditions of drainage, fertilization and sowing density. A General Linear Model was used (p<0.05) with the following factors: density 0,5 and 1 kg/100m², and fertilizing doses of 92 and 184 kg/N/ha, supplied as urea with or without draining material. To establish growth rate 5 cm high mowing was made, measuring the carpet height before each mowing. It was observed that the lowest values were registered in June, July and august; the greatest growth in September and October, and another increase since the end of November until January. Statistical analysis showed significant differences in the interaction: drainage throughout time and drainage-density. Consequently, it was possible to develop the following mowing frequency chronogram for the period considered: December, January, February, march, April, every 7 days; June, July, every 30 days; September, October, November, every 3 days; May and August, every 15 days.

Key Words: grass - mowing - growth - frequency

2 Tables, 2 Figures, 9 References

 Abstracts - No. 4 (2000) ISSN 0329-3602

Revista Científica Agropecuaria 4: 19-23 (2000)

PRELIMINARY HYDROCHEMICAL CHARACTERISTICS OF THE PARANÁ AQUIFER

Eduardo P. Vivot, María del Carmen Cruañes, Carlos J. Vesco(†)

Cátedras de Química y de Edafología. Facultad de Ciencias Agropecuarias. Universidad Nacional de Entre Ríos. C.C. Nº 24. 3100 Paraná, Entre Ríos. Argentina

Summary: Data obtained from a survey performed in 24 water wells in Paraná and Diamante Departments, in the Province of Entre Ríos, Argentina, were analyzed to state the hydrochemical characteristics of waters of the Paraná aquifer, which is an intermediate member of the homonymous Formation. This work is meant to contribute to the necessary and essential knowledge of the resource with regard to its important uses in farming settlements. The Paraná formation is a result of the deposits of marine ingresses during the Miocene in the Tertiary Age. Basically three levels define it. The intermediate level is entirely made of grey-whitish, small and medium-size grain sands, with a variable thickness which may fluctuates between 30-60 m. Preliminary characteristics of the Paraná aquifer indicate that is has waters with a medium-high rate of salinity, with electric conductivity which varies within a wide range, and a predominance of sodium bicarbonate. Results obtained allow waters to be typified according to the main agronomic uses. Water has good quality for animal consumption, particularly for bovines, whereas its use for crop irrigation has restrictions.

Key Words: Paraná aquifer - hydrochemical characterization - agronomics uses

1 Tables, 7 References

 Abstracts - No. 4 (2000) ISSN 0329-3602

Revista Científica Agropecuaria 4: 25-30 (2000)

ECONOMIC ANALYSIS OF MANAGING ALTERNATIVES AIMED AT OPTIMIZING THE USE OF "CARAGUATÁ" INFESTED NATURALIZED GRASSLANDS

José H. I. Elizalde, Rafael A. Sabattini, Víctor H. Lallana

Cátedras de Ecología y de Fisiología Vegetal. Facultad de Ciencias Agropecuarias. Universidad Nacional de Entre Ríos. C.C. Nº 24. 3100 Paraná, Entre Ríos. Argentina

Summary: The aim of this work was to present an economic analysis of different managing alternatives for controlling "caraguatá" in a natural grassland. Four treatments (T1, T2, T3, and T4) were carried out and each one involved three replications. T1 (control) and T2 (mechanical and chemical control) were placed in a fenced in plot to prevent animals from getting into the area. T3 (mechanical, chemical and grazing control) and T4 (grazing only) were placed in an open grazing area. T2 revealed a 68 % increase in grassland productivity and a decrease in "caraguatá" coverage and density: 74 % and 58 % less than T1, respectively. T4 showed a greater productivity rate (974 kg MS/ha/year) as compared to T3 (840 kg MS/ha/year). The productivity ratio calculated to asses cattle grazing showed an additional benefit in T3 (27.72 $/ha) in relation to T4 (6.6 $/ha). In both cases the grassland kept good productivity levels. Although T2 reached the highest grassland productivity, the costs of implementing this control practice make it not economically viable. The results of this test, however, show that it is worthwhile to undertake new trials to seek similar results with lower-cost herbicides.

Key Words: naturalized grassland - Eryngium paniculatum ("caraguatá") - control - economic analysis

4 Cuadros, 3 Figuras, 5 Referencias

 Abstracts - No. 4 (2000) ISSN 0329-3602

Revista Científica Agropecuaria 2: 31-38 (2000)

CLIMATIC RISKS IN AGRICULTURE AND CATTLE-RAISING: APPROACHES TO DAMANGE CAUSED BY HAIL

Anselmo Folmer

Cátedra de Organización y Planeamiento de la Empresa Agropecuaria. Facultad de Ciencias Agropecuarias. Universidad Nacional de Entre Ríos. C.C. Nº 24. 3100 Paraná, Entre Ríos. Argentina

Summary: The performance of a correct expert work involves field expertise in evaluating the extent of damage caused by hail. This monograph aim at providing professionals interested in this topic with the results obtained by an expert in cereal crop insurance against hail, bearing in mind that related reference material is very scarce. Several aspects to be taken into account during a professional assessment are dealt with, and a case study related to flax cultivation is included.

Key Words: expert's appraisal - survey - insurance

2 Cuadros, 5 Referencias