In direct planting, corn is the best

Corn cultivation has great advantages over others in the PD. However, it is necessary to observe a series of recommendations to avoid seeing a good business go under.

10.11.2015 | 21:59 (UTC -3)

In recent years, emphasis has been placed on planting various crops in a direct planting system, due to the advantages of this system when compared to the conventional system, mainly in relation to better soil conservation. It is currently estimated that, in Brazil, around 10 million hectares are under a direct planting system.

Direct planting has the characteristic of being a management system in which soil mobilization is avoided. This creates a new ecological environment - different from that existing in the conventional system - which results in a series of advantages for the farmer and the environment. Among these advantages, the following can be highlighted: erosion control, moisture conservation, weed control, improvement in soil structure and phytosanitary conditions of the crop, as well as greater savings in fertilizer and machinery.

Crop rotation is the basis of support for direct planting and, in this aspect, summer rotation, especially between corn and soybean crops, plays a prominent role. In addition to increasing their productivity (both in corn and soybeans), this rotation facilitates the control of pests, diseases and weeds, in addition to providing better use of nutrients.

Corn cultivation, in a cultural rotation program, offers additional advantages, due to the greater production and maintenance of crop residues (straw) on the soil surface. Experimental data shows that corn produces twice as much dry matter per hectare as oats, four times more than wheat and six times more than soybeans.

In addition to the normal care that the producer must take when installing direct planting, in the case of corn, the farmer must also have the following concerns:

A) Nitrogen fertilization must be reviewed. Although areas under direct planting for several years have higher levels of organic matter, nitrogen deficiency has been found in corn, with significant differences in relation to conventional tillage, when the crop sequence is predominantly grass. This effect, however, can be greatly reduced with the inclusion of one more legume in the rotation system. In general terms, a greater amount of nitrogen is recommended at sowing (30 to 40kg/ha) to reduce the effects of the initial nitrogen deficiency due to the immobilization of this nutrient. Top dressing nitrogen fertilization follows the same recommendations as the conventional system. In a well-established direct planting system, it is possible to save money on the use of phosphate fertilizer. Regarding potassium, no differences have been found between direct and conventional planting.

B) Another important aspect in direct corn planting is establishing the desired planting density. The occurrence of a lower than desired planting density is common in direct planting, where soil and planter conditions are not favorable. Where there is excess straw, poorly distributed straw, irregular microrelief, normally associated with soil with a higher moisture content than adequate, there may be a reduction in planting density, in addition to causing uneven emergence and delay in initial development. These problems can be aggravated if the quality of the planter is not good. In these cases, it is suggested to increase the quantity of seeds by 5 to 10% when adjusting the planter compared to conventional planting. It is also important to keep the seeding speed within the recommended limits.

The establishment of adequate planting density is also favored by the use of better quality seeds and adapted cultivars. In this aspect, high productivity cultivars are recommended, adapted to the region with good agronomic characteristics. In the case of direct planting of corn, emphasis should be placed on the use of cultivars that have better rooting and good initial vigor, so that adequate planting density and germination can be ensured, as well as rapid and uniform emergence.

C) The chosen cultivars must be tolerant to pests and diseases, considering that direct planting favors a higher incidence of microorganisms. In this aspect, crop rotation is an essential instrument, as the lack of an adequate rotation program could favor the occurrence and increasing proliferation of pests and diseases, in addition to the selection and perpetuation of weeds. Crop rotation often allows the control of pests, diseases and weeds (which could not be economically reduced with the use of agrochemicals alone).

The other operations do not have much difference between direct and conventional planting, remembering, however, that, in direct planting of corn, managing the straw produced is important, in order to avoid problems with the following crop. It is often necessary to use a spreader or straw chopper.

All considerations made so far refer to the direct planting of corn in the normal harvest. But, in Brazil, today there is the corn harvest, which already occupies more than two million hectares. In this planting system, corn is planted, without irrigation, after a crop in the normal season (generally early soybeans). In this case, the early soybean-corn rotation occupies the same area in the same agricultural year. Direct planting, in this case, has the additional advantages of greater water availability promoted by direct planting and the possibility of planting earlier, right after the soybean harvest, reducing risks in the production of safrinha corn. On the other hand, off-season corn will favor the production of straw necessary for the sustainability of direct planting.

José Carlos Cruz

Embrapa Corn and Sorghum

Mosaic Biosciences March 2024