Sowing corn on different surfaces

Sowing is one of the most important steps in establishing a crop. There are many factors, biotic and abiotic, that affect corn productivity. The potential for use and occupation of land depends on the environmental characteristics of the location. In the case of corn, soil and climate factors are the most important for the development of the crop.

Corn occupies the second position of the most produced crops in Brazil, being preceded by soybeans. In the 2019 harvests, there were more than 17 million hectares of cultivated area, representing an increase of 5,3% compared to the previous harvest. The estimated production for 2019, of 99,984 million tons, represented an increase of 23,9% in relation to previous production.

Corn is a crop of great importance for human and animal nutrition, energy generation with the production of fuel and raw materials for other purposes. Analyzing the space, based on information on land topography and vegetative canopy temperature, can provide management technologies accessible to rural producers.

The potential for use and occupation of a given area depends largely on the environmental characteristics of the location. Corn requires that the indices of climatic factors, especially temperature, rainfall and photoperiod, reach levels considered optimal, so that its genetic production potential is expressed to the maximum.

In areas where the slope of the land varies, the total radiation received during a production cycle differs, which may interfere with crop development. Physiological processes are influenced by climatic factors (precipitation, solar radiation and temperature) and physical-chemical parameters of the soil (water and nutrient availability), factors that generate parameters to be correlated in different terrains, observing changes in productivity.

Water deficiency can limit the functioning of plant activities, such as reduced absorption and accumulation of nutrients, changes in the root/shoot ratio and production of total dry mass; due to reduced root growth and water serving as the medium through which mineral nutrients move from the soil solution to the plant's roots.

With the objective of evaluating the growth of corn on different surfaces, depending on the slope of the terrain and exposure to sunlight incident on the plants, work was carried out at the Department of Engineering and Exact Sciences at Unesp/FCAV, Jaboticabal Campus, São Paulo, Instrumentation, Automation and Processing Laboratory (Liap).

The work was carried out in a structure that simulates surfaces with exposure to sunlight (North and South) and slopes (0%, 10%, 30% and 50%), with 10,5m2 (3,5m x 3m).

The surfaces were filled with previously homogenized soil, classified as Dark Red Oxisol, Eutrophic. The region's climate is Cwa type, with average annual precipitation of 1.400mm, average annual temperature of 22°C and average relative humidity of 70%.

The work was carried out during the 2018/19 harvest period. Irrigated, three and four day irrigation shifts were used during the crop cycle. Water replacement in the soil, during the irrigation shift, was carried out according to the sum of the crop's evapotranspiration.

The corn hybrid used was Pioneer P4285VYHR, which has the Roundup Ready gene and Leptra technology. The soil was manually disturbed in the sowing line.

Sowing was carried out manually, with the aid of a graduated ruler (Figure 1), with one seed being deposited per hole every 0,4m, totaling seven plants per row, respecting the population of 55 thousand plants per hectare. The spacing between the lines was 0,45m.

When sowing, fertilization of 250kg/ha of the formula 08-28-16 was used. Top dressing 20-00-20 was applied 30 days after sowing (DAS). Finally, nitrogen fertilization was carried out at 60 DAS.

Meteorological data for the period during which the experiment was conducted were provided by an Automated Meteorological Station, brand Davis Instruments, installed close to the experimental area, covering the corn crop cycle. The station was equipped with a Vantage Pro Plus Wireless data acquisition system, where global solar radiation was measured; temperature and relative humidity; wind speed and rainfall and reference evapotranspiration (ETo).

Two tensiometers with Bourdon-type vacuum gauges were installed in the center of each surface. These were calibrated in relation to mercury tensiometers, one installed at 20cm and the other at 40cm deep (Figure 2). Irrigation was carried out by drip with six hoses, drippers spaced 20cm apart, flow rate of 90L/h.

Meteorological components

In Figure 3, the maximum, minimum and average temperatures for the period during which the experiment was conducted are presented. It was observed that the highest temperature was 36,11°C at 14 days after sowing and the minimum temperature was 14,6°C at 40 days after sowing.

In Figure 4, the maximum, average and minimum air humidity values ​​were presented. A maximum humidity of 100% was observed on several days and a minimum, close to the experiment's harvest, was 24%.

According to the literature, the temperature and humidity values ​​obtained in this work are within those recommended for the correct development of corn, where the ideal temperature is around 35°C and humidity above 50%.

Figure 5 shows the global solar radiation values ​​during the experiment. It was observed that the amount of radiation incident on the corn canopy was different between treatments. The horizontal surfaces (0) accumulated a greater amount of global radiation, 2212,91 MJ m -2 d-1, and, consequently, a greater amount of photosynthetically active radiation, 911,91 m -2 d-1. Followed by the horizontal surfaces, the 10%S treatment received 2201,3 MJ m -2 d-1 of global radiation and 907,1 MJ m -2 d-1 of PAR. The other treatments accumulated values ​​between 2203,0 and 1989,5 MJ m -2 d-1 and 907,9 and 819,2 MJ m -2 d-1 for global radiation and PAR, respectively.

For the variable plant height, Figure 6, higher averages were found on surfaces 30S, 10S and 30N, respectively. It was observed that the values ​​did not follow the highest radiation values. Because the amount of radiation received is quite close, plant height values ​​are also estimated to be close.

Phytotechnical components

For the variable plant dry matter mass (MMS), higher values ​​of 10N, 30S and 10S were observed, respectively (Figure 7). A greater amount of MMS is interesting for the producer, whatever the purpose of corn production: animal feed, soil cover. Increasing the amount of MMS without reducing grain mass is a task to be followed, as grains have greater added value and greater nutritional value for human and animal nutrition.

For the productivity variable (Figure 8), higher averages were observed on surfaces 30N, 10S and 50S. The highest average productivity, 13,2t/ha, was obtained on the 30N surface, followed by 12,5t/ha on the 10S surface. These values ​​are above the average found in Brazil, which is 5,35t/ha.

These values ​​were obtained due to the management of the crop, where fertilization, irrigation and weed control were carried out. The region's soil conditions, where a greater amount of clay, amount of radiation, humidity and temperature predominates, may also have influenced the correct development of the crop. As already mentioned in this work, the set of soil and climate conditions means that the crop reaches its maximum genetic potential.

Final considerations

The exposure to which the plants were subjected can influence the development of the corn crop. In this experiment, greater productivity was found when the plants were exposed to the North, at a 30% slope of the terrain. The geographical conditions of the land must be taken into consideration when planting crops in the field, so that the available inputs and those that will be offered can be made better use of.

Jean Lucas Pereira Oliveira, Marcelo Rodrigues Barbosa Júnior, José Eduardo Pitelli Turco, Carlos Eduardo Angeli Furlani, Armando Lopes de Brito Filho Unesp

Cultivating Great Crops November 2020

With each new edition, Cultivar Grandes Culturas publishes a series of technical content produced by renowned researchers from all over Brazil, which address the main difficulties and challenges encountered in the field by rural producers. Through research focused on controlling the main pests and diseases in the cultivation of large crops, the Magazine helps farmers in the search for management solutions that increase their profitability. 

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