Ivo Ambrosi

Lucratividade e risco de sistemas de produção de grãos combinados com pastagens de inverno

n†The objective of this work was to evaluate the profitability and risk of grain production systems combined with annual winter pastures, under no-tillage system. The experiment was carried out in Passo Fundo, RS, Brazil, in a†six-year period (1990-1995). The systems were: system†I (wheat/ soybean, grazed black oats/soybean, and grazed black oats/soybean); system†II (wheat/soybean and grazed black oats†+ grazed common vetch/corn); system†III (wheat/soybean, grazed black oats†+ grazed common vetch/soybean, and grazed black oats†+ grazed common vetch/corn); and system†IV (wheat/ soybean, white oats/soybean, and white oats/soybean). An†experimental design in blocks at random, with three replications and plots with 500†m 2 , was used. Three types of analysis were applied to the net return of systems: mean-variance analysis, distribution of accumulated probability, and stochastic domi- nance. When mean-variance analysis was used no significant differences were observed in the systems studied. By†the distribution of accumulated probability, the selection of an alternative depends solely and exclusively on the level of risk chosen by the decision-maker. By†the stochastic dominance method, system†II showed to be the best production alternative to be offered to farmers from both profit and lower risk standpoints.

Effect of crop rotation on yields, soil chemical characteristics, and economic returns of zero-till barley in southern Brazil

Abstract The severe soil degradation and low income problems of producers in southern Brazil are being attributed to the widespread use of wheat ( Tricticum aestivum L.)-soybean ( Glycine max. (L.) Merr.) or barley ( Hordeum vulgare L.)-soybean double-cropping systems, combined with extensive use of mechanical methods of soil tillage. This 6 year study, which was conducted at Guarapuava in south-central Parana, compared the effects of four zero-tillage barley rotations on grain yields, soil chemical characteristics, and economic returns. The rotation treatments included: barley-soybean, barley-soybean-vetch ( Vicia sativa L.)-corn ( Zea mays L.) (1 year without barley), barley-soybean-flax ( Linum usitatissimum L.)-soybean-vetch-corn (2 years without barley), and barley-soybean-flax-soybean-oat ( Avena sativa L.)-soybean-vetch-corn (3 years without barley). Yields of barley in the traditional barley-soybean rotation increased by an average of 9% (range of 4–20% higher) by including other winter crops in the rotation, presumably due to a reduction in diseases and pests. Extending the rotation length beyond one winter without a barley crop provided no additional benefit to barley yields. Yields of soybean were lower in several years when grown after flax due likely to allelopathic effects, and after oat due to problems with proper seed placement under the high crop residue conditions. Soil pH and Al concentration tended to revert to the initial levels within 4 years after application of lime. Soil organic matter increased under all rotations reflecting the large amounts of residues being returned to the soil and the low soil losses under zero-tillage management. Costs of production (expressed in US dollars) were highest for the barley-soybean rotation (

Rendimento e nodulação de soja em diferentes rotações de espécies anuais de inverno sob plantio direto

464 vs.

Risco de sistemas de rotação de culturas de inverno e verão sob plantio direto

380 ha −1 for mixed rotations). The most profitable cropping system was the 1 year without barley rotation under most economic situations examined. It was profitable to substitute flax or oat for barley when the price ratios of flax to barley and oat to barley exceeded 1.92 and 0.97, respectively. Similarly, it was profitable to substitute corn for soybean during the summer growing season when the price ratio of corn to soybean exceeded 0.39. The traditional barley-soybean rotation displayed the greatest income variability or riskiness. The study concluded that there is both agronomic and economic merit for area producers to adopt these new production opportunities.

Lucratividade e risco de sistemas de manejo de solo e de rotação e sucessão de culturas

The different preceding crops were compared in relation to soybean yield and nodulation during four years at the Faculdade de Agronomia e Medicina Veterinaria, in Passo Fundo, State of Rio Grande do Sul, Brazil. Four production systems with annual winter pastures were tested, in which soybean was sown after different winter crops (white oats, grazed black oats, grazed black oats + grazed common vetch, and wheat). Both in winter and summer the crops were grown under no-tillage. An experimental design of blocks at random, with three replications and plots with 500 m2, was used. No significant differences between type of preceding crop and soybean yield were found in the mean of years . After five years of no-tillage, an abundant nodulation in soybean was observed in all production systems. Soybean grown after white oats, grazed black oats, grazed black oats + grazed common vetch, and wheat may be included, without any loss, in the different systems studied.

Analise de risco em quatro sistemas de rotacao de culturas para trigo, num periodo de dez anos, em Passo Fundo, RS.

From 1984 to 1993, in Guarapuava, Parana (PR), Brazil, four crop rotation systems for wheat were assessed: system I (wheat/soybean); system II (wheat/soybean and common vetch/corn, from 1984 to 1989, and wheat/soybean and white oats/soybean, from 1990 to 1993); system III (wheat/soybean, flax/soybean, and common vetch/corn, from 1984 to 1989, and wheat/soybean, common vetch/corn, and white oats/soybean, from 1990 to 1993); and system IV (wheat/soybean, legume/corn, barley/soybean, and white oats/soybean). A randomized block design having four replications and plots totalizing 60m2 was used. Risk analysis over that period is presented in this paper. Two types of analysis were applied on the net return of the systems: mean-variance analysis and risk analysis (safety-first and stochastic dominance). Separation of system II as the best alternative to be offered to the one who decides was feasible by both types studied. The system II showed the highest profit and the lowest risk to be offered to the farmer, as compared to the remaining systems studied.De 1984 a 1993, foi conduzido, em Guarapuava, PR, um experimento reunindo quatro sistemas de rotacao de culturas para trigo: sistema I (trigo/soja); sistema II (trigo/soja e ervilhaca/ milho, de 1984 a 1989, e trigo/soja e aveia branca/soja, de 1990 a 1993); sistema III (trigo/soja, linho/soja e ervilhaca/milho, de 1984 a 1989; e trigo/soja, ervilhaca/milho e aveia branca/soja, de 1990 a 1993); e sistema IV (trigo/soja, leguminosas/milho, cevada/soja e aveia branca/soja). O delineamento experimental foi de blocos ao acaso, com quatro repeticoes e parcelas com area util de 60m2. No presente trabalho, mostra-se a analise de risco nesse periodo. Foram aplicados dois tipos de analise na receita liquida dos sistemas: analise da media variância e analise de risco (distribuicao de probabilidade acumulada e dominância estocastica). Pelos dois tipos estudados, foi possivel separar o sistema II como a melhor alternativa a ser oferecida ao tomador de risco. O sistema II apresentou a maior lucratividade e o menor risco a serem oferecidos aos agricultores, em comparacao aos demais sistemas estudados.

Soybean yield and nodulation in different annual winter crops under no-tillage

Crop rotation and succession systems lesser the risk level due to diversification of cultivities. Soil tillage and crop rotation and succession systems were assessed in Passo Fundo, RS, Brazil, from 1994/95 to 1997/98. Four soil tillage systems - 1) no-tillage, 2) minimum tillage, 3) conventional tillage using a disk plow, and 4) conventional tillage using a moldboard plow - and three crop rotation and succession systems [system I (wheat/soybean), system II (wheat/soybean and common vetch/sorghum or corn), and system III (wheat/soybean, common vetch/sorghum or corn, and white oats/soybean)] were compared. An experimental design of randomized blocks with split-plots and three replications was used. The main plot was formed by the soil tillage systems, while the split-plots consisted of the crop rotation and succession systems. Two types of analysis were applied to the net return of soil tillage and crop rotation and succession systems: mean-variance and risk analysis. By the mean-variance analysis, no-tillage and minimum tillage, which presented higher net return, were the best alternatives to be offered to the farmer. By the stochastic dominance analysis, no-tillage and crop rotation with two winters without wheat showed the highest profit and the lowest risk.

Sistemas de produção alternativos de triticale, sob plantio direto, em Passo Fundo, RS

During ten years (1980 to 1989), at the Embrapa-Centro Nacional de Pesquisa de Trigo (CNPT), in Passo Fundo, RS, Brazil, the effects of crop rotation systems on wheat (Triticum aestivum L.) were assessed. Four rotation systems for wheat were studied: system I (wheat/soybean); system II (wheat/soybean, rapeseed/soybean, barley/soybean, lupine or serradella/corn); system III (wheat/soybean, arrowleaf clover/arrowleaf clover, and arrowleaf clover/corn, from 1980 to 1983, and wheat/soybean, white oats/soybean, and common vetch/corn, from 1984 to 1989); and system IV (wheat/soybean, rapeseed/soybean, flax/soybean, and lupine or serradella/corn). A randomized complete block design, with four replications and plots with 120 m2, was used. Risk analysis over that period is presented in this paper. Two types of analysis were applied to the net return of the systems: mean-variance analysis and risk analysis (safety-first and stochastic dominance). By the mean-variance analysis, systems II and IV showed higher net returns as compared to systems I and III. The system II showed the highest profit and the lowest risk to be offered to the farmer, as compared to the remaining systems studied.

Yield and nodulation of soyabeans in rotations with different annual winter crops in a no-tillage system.

The different preceding crops were compared in relation to soybean yield and nodulation during four years at the Faculdade de Agronomia e Medicina Veterinaria, in Passo Fundo, State of Rio Grande do Sul, Brazil. Four production systems with annual winter pastures were tested, in which soybean was sown after different winter crops (white oats, grazed black oats, grazed black oats + grazed common vetch, and wheat). Both in winter and summer the crops were grown under no-tillage. An experimental design of blocks at random, with three replications and plots with 500 m2, was used. No significant differences between type of preceding crop and soybean yield were found in the mean of years . After five years of no-tillage, an abundant nodulation in soybean was observed in all production systems. Soybean grown after white oats, grazed black oats, grazed black oats + grazed common vetch, and wheat may be included, without any loss, in the different systems studied.

Analysis of rotation systems for winter and summer, under no-tillage

From 1987 to 1991, in Passo Fundo, RS, Brazil, the effects of production systems on triticale crop were assessed at the Centro Nacional de Pesquisa de Trigo. Five systems for triticale were studied: system I (triticale/soybean), system II (triticale/soybean and black oats/soybean, from 1987 to 1989, and triticale/soybean and white oats/soybean, from 1990 to 1991), system III (triticale/soybean and common vetch/corn), system IV (triticale/soybean, black oats/soybean and common vetch/corn, from 1987 to 1989, and triticale/soybean, common vetch/corn and white oats/soybean, from 1990 to 1991), and system V (triticale/soybean, triticale/soybean, black oats/soybean and common vetch/corn, from 1987 to 1989, and triticale/soybean, triticale/soybean, common vetch/corn and white oats/soybean, from 1990 to 1991). An experimental design of blocks at random with three replications and plots with 24 m2 was used. Economic analysis over that period is presented in this paper. Over the period in which the climatic conditions were normal, system III was the best alternative to be offered to farmers from profitability standpoint. When climatic conditions were adverse, system II showed higher economic return, as compared to the remaining systems studied.