Cultivo da mandioca sob bases agroecológicas: estado da arte, adubação verde e supressão de plantas espontâneas no territorio do cone sul de Mato Grosso do Sul

Abstract

During the period 2010-2012, were developed research actions involving farmers, as well as an experimental area, both in the Southern Cone Territory of Mato Grosso do Sul State. Thus, this study aimed to know the state of the art concerning the cassava grown under agroecological bases in the territory, in addition to studying the behavior of green manure spring / summer for the purpose of suppressing weeds, as well as for improving the cultivation of cassava. The research work carried out were organized into three chapters, the first of which is "Socioeconomic aspects, agronomic and environmental inherent to cassava cultivation under agroecological bases in the Territory of the Southern Cone of Mato Grosso do Sul”. The work was developed in the Territory of the Southern Cone of the of Mato Grosso do Sul State, involving 45 families of traditional farmers and settlers in the period September to December 2012, with the aim of knowing and analyzing socio-economic, agronomic and environmental concerning the cassava cultivation bases under agroecological that territory. To identify development experiences, we used a sampling methodology in snow-ball aiming to meeting potential key informants and farmers involved with the culture. In each production unit previously identified, there was a guided tour and at the same time, he was interviewed the farmer responsible from a semi-structured script containing open and closed questions. The results showed that cassava is the main activity for the purpose of generating income, with average yield between 24:25 t ha-1; the diversification of activities in production units among the settlers is more representative; farmers traditional use green manure more than settled farmers, and these adopt more often hand weeding and animal traction over traditional, due to the greater availability of skilled labor; farmers have technical assistance, but sporadic and predominantly unsatisfactory. Farmers consider Erinnyis ello and ants as major pests in cassava growing areas, using biological, grouts based on plant extracts and methods for physical and mechanical control. Predominate farmers who participate in class organizations, are in associations or cooperatives; farmers and settlers traditional family expressed interest in adding value to production; there is a lack of research that contributes to the reduction of the production cost of cassava under agroecological bases. The second chapter addressed the subject: "Suppression of weeds by using green manuring in the system under agroecological bases in the Southern Cone Territory of Mato Grosso do Sul State". The objective to know the potential of soil cover and suppression of weeds by manure green spring/summer, in different stages of development and after management (cut) for 90 days of crop cassava. The study was carried out during the 2010/2011 in the municipality of Itaquiraí, located in the territory of the Southern Cone of Mato Grosso do Sul State, in a system managed under agroecological principles. The treatments consisted of different green manure species and arrangements: Crotalaria juncea, Cajanus cajan, Canavalia brasiliensis, Canavalia ensiformes, Penissetum americanum, Crotalaria juncea and Penissetum americanum intercropped; Mucuna aterrima, Sorghum bicolor, mixture of all green manures used in the study (Canavalia ensiformes, Canavalia brasiliensis, Mucuna aterrima, Cajanus cajan, Crotalaria juncea, Penissetum americanum and Sorghum bicolor) and a control plot fallow. We used a randomized block design with four replications. Evaluations of soil covered by green manure and the weeds were performed at 45, 90 and 105 days after emergence of green manures. At 11 days after cutting the green manures was implanted cassava through reduced tillage. At 30, 60 and 90 days after planting of tuberose were evaluated concerning the rate of soil covered by weeds and dry mass produced. The results show that green manure species exert suppressive effect of weeds during the life cycle, as well as during the first months after its management (cut), acting as mulch. The third chapter covers the study "Performance of green manure and effects on cassava cultivated in succession under agroecological bases in the Southern Cone of Mato Grosso do Sul State", with the objective of identifying the potential of phytomass and nutrient accumulation in shoots of green manure and performance of cassava grown in succession. The study was conducted in the period from 2010 to 2012, in the municipality of Itaquiraí, in the Southern Cone Territory, Mato Grosso do Sul State, in a typical oxisol. The experimental design was a randomized block with four replications. The treatments were: Canavalia ensiformes, Canavalia brasiliensis, Mucuna aterrima, Sorghum bicolor, Cajanus cajan, Penissetum americanum, Crotalaria juncea and Penissetum americanum intercropped, mixture of all green manures used in study and witness fallow. The parameters evaluated at 105 days after emergence of the green manures were: dry matter accumulation, of nitrogen, phosphorus, potassium, calcium, magnesium and sulfur in the shoots of coverage. At 11 days after cutting the green manure, cassava (IAC 576) was planted in a minimum tillage system. During the cassava harvest, 12 months after sprouting cuttings were evaluated for plant height, fresh weight of shoot, root weight and harvest index. The results showed that the mixture of green manures and C. juncea showed higher dry matter accumulation in shoots of plants in the other treatments, as well as the accumulation of most nutrients. The C. cajan showed greater accumulation of nitrogen, phosphorus and sulfur in the shoots, as well as millet for phosphorus, potassium and sulfur. Cassava showed the best performance when grown in succession to the mixture of green manures and C. juncea.