Opening Virgin Cerrado Land

Opening Cerrado Land

The native vegetation of Brazil's cerrados varies considerably from one area to another. In Western Bahia a fairly typical native vegetation is a combination of grasses and sparse to dense low-growing shrubs and perhaps 20 to 200 trees per ha. The trees seldom exceed 10 meters in height or 250 mm in diameter.

On most cerrado land, initial clearing is easily accomplished by dragging a 100-meter, one-inch steel cable between two large tractors. Where vegetation is dense, a heavy 75-meter chain may be used instead of a cable.

Clearing takes place during the rainy season. Most of the tree and shrub roots are pulled out of the wet soil by the cable or chain. Woodcutters harvest the larger trees for firewood and pile and burn the brush. If roots remain in the soil, a pass or two with a heavy, straight-shank chisel, brings them to the top.

Discing, Liming and Planting

After vegetation is removed, a heavy 32-or 36-inch disc is used to open the soil. Laborers manually remove any remaining roots. Two to three tons of limestone are applied, and the soil is again disked with a heavy disk. After liming, the land is worked with a lighter disk, field cultivator and harrow and planted to upland rice.

Clearing, liming and planting take place over a period of 6 to 9 months. Clearing is done at the peak of the rainy season, and rice is planted at the beginning of the next rainy season. Clearing costs per ha, not including lime and fertilizer, range between US$50 and US$100 depending on the vegetation. Most of the clearing in Western Bahia is done by local contractors.

Native fertility of cerrado soils is extremely low, and the application of limestone is a critical first step in fertility improvement of newly opened land. Aluminum saturation, low available N, P and K and micronutrient deficiencies are the rule. For viable agricultural production, the soil must be limed, fertilized and treated with micronutrients.

Upland Rice First Crop

Upland rice is traditionally the first crop to be planted on newly opened cerrado lands. It is a rustic crop that tolerates poor soil fertility. Although upland rice grown on newly opened land might yield only 20 to 30 sacks per ha, it generates income as the limestone is stimulating biochemical actions in the soil. Agronomists now recommend that upland rice seed be treated with a soybean inoculate. While the inoculate has no effect on rice, it interacts with organic matter in the soil to provide a more favorable environment for soybeans planted the following year.

Fertility and Time

While biochemical reactions are essential to enhanced fertility of cerrado soils, these interactions take place primarily during the six-month rainy season. During the dry season, these reactions essentially stop. For this reason, fertility of dryland soils is highly correlated with the number of crop production cycles.

Most dryland cerrado soils reach high fertility levels after five or more years of cropping. If newly opened soils are irrigated and double- or triple-cropped, the period of time to achieve high fertility is shortened. Soybeans are typically planted on newly opened dryland soils between the second and fifth years after opening.

Fertilization and Yields

For soybeans produced in Western Bahia typical soil fertility recommendations include, on a per ha basis: 2 to 3 tons of limestone, 80kg of P, 80 to 90 Kg of K2O, 20kg of sulfur, 1kg of zinc, 1 kg of copper, 1.5 to 2kg of manganese and 400g of boron. In addition, fertility recommendations call for micronutrient applications via seed coating: 1.2g of cobalt and 12 to 15g of molybdenum per 60 kg sack of seed. Expected yield of second year soybeans is 20 to 40 sacks per ha.

Third-year soybean yields will be about 50 sacks per ha with recommended applications of limestone, fertilizer and micronutrients. Per ha applications are 400 to 500 kg of limestone, the same levels of P, K, So and Zn as the second year, and foliar applications of 300g of manganese and 100g of copper.

Recommended limestone, fertilizer and micronutrient applications for fourth and successive year soybeans are the same as the third year. Yields will run 50 to 60 sacks per ha, depending on the amount and distribution of rainfall.

Corn and Cotton Production

After the fifth year, soil fertility will be sufficient for corn production. Corn is new to Western Bahia and farmers are still learning about the crop. Yields are relatively low--between 120 to 150 sacks per ha, but profits from corn have been better than those from soybeans in recent years. Corn requires applications of about 100 kg of N, P and K, and roughly the same limestone and micro-nutrient applications as soybeans.

Dryland cotton production is not feasible in Western Bahia until the soil has been planted to soybeans and corn for about 7 years. On average during the past three years, cotton production and area doubled each year. The increased plantings are directly related to soil fertility improvement.

Cotton appears to have great potential in the area. Yields and quality are exceptionally high, and net profit is greater than that of any other dryland crop. Some believe the Barreiras area will become Brazil's number-one, cotton-producing region.

Photos

Newly cleared cerrado before final cleaning

Wood removed during clearing of heavy cerrado

Brush piles ready to be burned on newly opened cerrado