Large-scale commercial agriculture is primarily cattle-raising, both for beef and milk. Native vegetation is typically completely removed for the establishment of planted pastures, which cause soil compaction and erosion. There is also excessive and inappropriate use of herbicides, which increase productivity, but lead to negative effects on animal health and soil microbiology. There has been a recent increase in milk production using more productive European breeds of cows that are not as resistant to drought and harsh conditions, leading to problems with pest control and inappropriate use of chemicals. Still, although the NE has 19.0% of Brazil's dairy cattle and more family farmers in Sergipe have cattle than plant beans, manioc or corn, it produces only 11.0% of the milk. This gap in productivity requires more pasture land per liter.
The main commercial crops for large scale agriculture include corn (maize) and cotton. Irrigation is more common in largescale farming in northern Sergipe where there is an abundance of water from the São Francisco River but is being increasingly used on large scale to cover multiple farms. However use of irrigation schemes for water on large estates can have negative impacts on LD. Drip irrigation is far preferable to micro-aspersion, which is preferable to macro-aspersion or flooding, but costs much more. Within the SAS large-scale irrigation projects are currently limited to projects in two municipalities involving 333 farms covering 3,980 hectares. One third of this area (1,360 ha) is based on irrigation with macro-aspersion, which causes salinization and alkinization of the soil, making it unsuitable for crops other than saltbush (Atriplex genus). Such irrigation will increase when the planned Xingó Canal transposition to the south of the São Francisco through Bahia into Sergipe becomes a reality. The 306 km of this canal, the largest investment ever in water in Sergipe, to be built by the São Francisco and Parnaíba Valleys Development Company (CODEVASF), can provide benefits for human consumption, crops, livestock and industry, but the infrastructure can also have negative impacts in the five municipalities through which it passes in the SAS, depending on the irrigation practices adopted. Irrigation will be controlled by INCRA. In Canindé do São Francisco, it is administered by the Water Resources and Irrigation Development Company (COHIDRO). While micro-aspersion or drip irrigation are less damaging, these more modern techniques lack adequate soil conservation practices. Outside the best irrigation projects, irrigation by direct flooding of the soil is practiced. In extreme cases, excessive flooding has caused runoff channels and gullies, increased soil erosion, the collapse of stream and river beds, siltation of river courses and reduced soil quality. Erosion nearby in Ceará has been measured at 52,114 kg/ha in experimental conditions.
Agriculture at various scales is being increasingly mechanized with tractors dragging modern ploughs replacing traditional ploughs using animal traction. This mechanization is associated with increased maize planting, reduced land preparation time and less crop rotation. Reduced soil quality means lower productivity (yields) of crops. Little use of contour lines results in deeper furrows and increased surface runoff, soil erosion, compacting and loss of infiltration capacities. More runoff means less evapotranspiration and less rainfall farther inland. High use of herbicides, pesticides and fertilizers without proper management is also contributing to soil degradation and reduction of pollination. More than 200 pesticides are in use in the Semiarid region.
Over exploitation of wood
Wood harvesting is ubiquitous in the entire Northeast region. One third of the energy matrix is firewood, with 25 million m3 per year. Firewood is used by 70% of families for cooking. The extraction of 25 million m3 of wood to provide energy for industries such as gypsum and ceramics production and for commercial and residential purposes, feeding 40% of the energy matrix of the region, has caused negative impacts, although it could be sustainable. In states where Caatinga vegetation is still extensive, work undertaken by UNDP/FAO over the past 20 years has shown that sustainable management of Caatinga for fuelwood is feasible and regenerated forest can reach the same volume and species composition after 15 years. However, in the case of Sergipe, where large forest remnants cover only 13% of the total area, management for conservation, regeneration and restoration is required. In Sergipe, there are 80 brick and tile industries using fuelwood to manufacture bricks and tiles from raw clay. As the industrial sector expands due to urbanization and construction of brick and tile houses in rural areas, pressures for fuelwood extraction will continue to rise. Strengthened oversight is required to ensure that extraction from remaining forest is controlled. In the semiarid areas, encroachment into existing forest reserves still occurs especially during the dry season and between harvests, when wood extraction and sale complements household income. Encroachment on Legal Reserves and Areas of Permanent Preservation is linked to weak enforcement of the law, which was not taken very seriously in the past.
Wood is also harvested for fence posts. For example, just to separate the existing 4,827 lots in settlements in the SAS with an average of 20 hectares with perimeters of 1,800m would require nearly 9,000 km of fencing. With an average of 1.5 m. between posts, this would amount to 6 million fence posts. Since they need to be replaced every 5 years, the demand in this estimate is an average of 1,200,000 new fence posts per year. Subdivision of lots to separate livestock from crops increases the number needed, as does the requirement to keep livestock out of the areas protected by the Forest Code, the Legal Reserves (LR) and Areas of Permanent Preservation (APP). Electrified fences with only a few thin posts work for cattle, if there is electric power available, but they do not work for goats.
Hunting
Hunting, mostly for purposes of supplementing protein from other sources, is practiced as a result of low income levels and limited livestock productivity. It disturbs the ecological balance by reducing populations of species that play key roles in avoiding or remediating land degradation through maintenance and recovery of ecosystems. For example, many species of birds and mammals are essential for seed dispersion and armadillos help control termites and leaf-cutting ants, which attack crops and gardens.
