Coffee plantations require more detailed information than other plantations, according to Felipe Lopes, a specialist with Geoplanta Precisão.
At the O’Coffee estates detailed results from more than a thousand soil samples were obtained from six farms and plotted on a digital topographic map that was created by scanning aerial photographs supplemented by ground surveys.
Every hectare of the farm is plotted.The GIS system then calculates the distance between sample locations. Overlaying results of the soils analysis reveals the content of each nutrient in the soil. This enables farmers to determine with great accuracy different doses of fertilizers for each point.
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In the field “the crop receives different amounts of fertilizers based on local levels of chemicals essential to coffee production,” explains Edgard Bressani, c.e.o.
Usually samples are taken every five hectares for seasonal plants, he explains. Coffee plants, however, require a minimum of one sample per hectare. Soil and leaves are analyzed at different stages of the growth cycle.
“The stage of plant growth and its purpose will recommend better applications,” according to Lopes.
The first step is knowing the soil texture. A scanner that generates an electromagnetic field is towed behind the tractor to measure the electrical conductivity of the soil.
One goal is to detect areas high in clay which is highly conductive and easy to spot.
After that, samples are collected and submitted by lab analysis in order to map other features such as nutritional and chemical elements.
Readings correlate closely with soil properties that affect crop productivity such as texture, drainage, salinity and the level of organic material. A field sample is then taken to confirm results. It takes two employees an average of three weeks to assess 1,000 hectares, explains Lopes.
A huge amount of data is collected on plant nutrition, production levels, pruning details and the space between plants.
“This work is done only once because the soil texture will not change with time,” according to Lopes. A survey costs about $13.30 (R$50) per hectare. The lab analysis adds another $15.95 (R$60) per hectare.
Farmers then determine which fertilizer is needed and how much to apply per hectare and whether soil correction is needed before introducing fertilizers in the field. “If the pH is not favorable, for example, the field will not absorb the needed nutrition,” notes Lopes.
Once the inputs are decided the tractor and its trailer are guided by a global positioning system mounted in the cab.
Production levels and nutritional needs vary with each crop making it necessary to repeat this step ever year at a cost of $11 (R$45) per hectare.