Evolution and current status of soybean production in northwestern Argentina

DEVANI, M; PÉREZ, D; PLOPER, L.D.; OLEA, I; SALAS, H; LEDESMA, F; LENIS, J

Foz do Iguassú

Conferencia; VII World Soybean Research Conference (VII WSRC).; 2004

Embrapa SOJA y WSRC Continuing Committee

The provinces of Tucumán, Salta, Jujuy, west of Santiago del Estero and southeast of Catamarca are part of the region known as northwestern Argentina (NWA), located between the 22º and 29º Latitude South and the 63º and 68º Longitude West. In this area, the soybean crop occupies around 700.000 ha. Tucumán stands out due to its active participation in the research, development, and diffusion of this crop in the region. At first, soybean was planted in cattle areas or with scrubland non-capable for the development of the traditional crops. Later it displaced these crops of marginal areas for them, and finally, the use of an advanced technological package, allowed it to settle down in marginal areas. The growth of soybean production in NWA is a consequence of the increase in planting areas and yields, resulting from research work. Currently, average yields and total soybean production in NWA are around 2.500 kg/ha and 1.750.000 t, respectively. In spite of representing only 5% of the national production, the crop is very important for the regional economy. The distribution of maturity groups in cultivars available in the 1980s was stable, using mainly group VIII (70%) and IX (30%). The available materials, had been selected or generated locally by public institutions. The last decade was marked by a continuous replacement of soybean cultivars and changes in the distribution of maturity group, caused by different factors such as disease problems, environment changes, new tillage practices, and the appearance of transgenic soybean. During the 2002/2003 growing season, the distribution by groups of maturity was the following: group VIII: 80%, groups IV and V (indeterminate): 3.5%, group VI and VII: 16% and group IX: 0.5%. The decreasing structural stability of the soil and the monoculture of soybean in NWA caused degradation of soils during the 1970s and 1980s. Currently, more than 95% of the area with soybean is under a no-tillage and 40% is fertilized with phosphorous. No-tillage and the use of short groups, changed the row spacing to 0.52 m with increments in the population density. An average of 1.5 treatments of glyphosate per ha are carried out for weed management in transgenic soybean and the mixture of this herbicide with diclosulam applied in early post-emergency is used for the control of different species of genus Ipomoea. The most important pests are: a complex of curculionids (Sternechus pingui and Promecops carinicollis), cutting worms, caterpillars (Anticarsia gemmatallis and Rachiplusia nu), and a complex of bugs (Nezara viridula and Piezodorus guildinii). At present, the main diseases in the region are sudden death syndrome (Fusarium solani f.sp. glycines), frogeye leaf spot (Cercospora sojina), charcoal rot (Macrophomina phaseolina), and the late season fungal complex (Septoria glycines, Cercospora kikuchii, Corynespora cassiicola, Phomopsis spp., Alternaria spp., and Colletotrichum spp.). Sclerotinia stem rot (S. sclerotiorum) and other root rots (Fusarium spp.) appear occasionally and are not widespread in NWA.