Corn emergence speed

In corn cultivation, periodic soil preparation provides several effects for its implementation, one of which is the speed of seedling emergence.

The corn (zea mays L.) is among the three most cultivated cereals in the world (Teixeira & Costa, 2010); In Brazil alone, production was around 70 million tons in the 2015/2016 harvest, which kept the country as the third largest producer in the world (CONAB, 2016). This large production is partly destined for the food industry to obtain products such as: canned sweet corn, bran, cornmeal, corn flour, etc.; and another part intended for animal feed, such as silage.

For production to achieve significant results, constant care is necessary from soil preparation to harvest. This includes the time for seedling emergence, which under ideal conditions occurs four to five days after sowing, while under unfavorable conditions this time can be extended by two weeks or more (Magalhães & Durães, 2002). Another important point that must be analyzed is the type of soil preparation used.

The conventional planting system is widely used in corn cultivation, as it is responsible for providing improvements in the effectiveness of plant development and soil attributes, in addition to reducing or eliminating possible problems caused by certain pests, as this type of planting is which causes more damage (Oliveira & Bezerra, 2013). However, the equipment used in soil preparation can influence the development and productivity of corn.

Conventional soil preparation provides several effects for the installation and maintenance of corn crops. That said, a study was conducted in one of the experimental fields at the Federal University of Viçosa, Campus Paranaíba River – MG, which has an average altitude of 1100 meters, with the objective of evaluating the influence of the disc plough, rotary hoe and the intermediate plow harrow on the MG 744 MORGAN hybrid seedling emergence speed process. The area was classified as a dystrophic RED – YELLOW Oxisol, clayey texture, having been cultivated with grains since 2014 with the same preparation systems.

Field tests 

The experimental design was completely randomized (DIC) with three treatments and four replications, with soil preparation treatments being: disc plow, intermediate harrow and rotary hoe. Thus, resulting in a total of twelve experimental units, where each plot consists of an area of ​​100 m² (10 x 10 m), these are separated by spaces, also of 100 m², intended for the traffic of machines, maneuvers and adjustments of the equipment.

When sowing corn for silage, the MG 744 MORGAN hybrid was used, which has a cycle of 115 days (from planting to grain harvest), in a stand of 72.000 seeds ha^-1 and expected productivity of 50.000 kg of grains ha^-1, spacing between rows of 50 cm and around 60 days to ensile. Sowing was done at an average depth of three cm, using MAP 10 50 00 at a dosage of 300 kg ha^-1 as planting fertilizer, protected urea was used for top dressing at a dosage of 400 kg ha^-1, no seed treatment was carried out.

To determine the number of emerged seedlings, an interval of two meters was used in the central row. According to Carvalho Filho et al. (2006) an emerged seedling was considered to be one that broke through the soil and could be seen with the naked eye, from any angle. The demarcation of two meters in the central row was carried out as follows: starting at the edge of the plot, two meters were measured, a stake was fixed, from that stake another two meters were measured, where a second stake was fixed , so the count of emerged seedlings was done in the interval between cuttings. Therefore, the count was carried out daily until the number of seedlings stabilized for three consecutive days, as proposed by Silva (2002), then obtained from equation (1) (Edmond and Drapala, 1958), the average number of days for seedling emergence.

Where: M - average number of days for corn seedlings to emerge; N1 - number of days elapsed between sowing and the first seedling count; G1 – number of seedlings emerged in the first count; N2 - number of days elapsed between sowing and the second seedling count; G2 - number of seedlings emerged between the first and second counts; Nn - number of days elapsed between sowing and the last seedling count; Gn - number of seedlings emerged between the penultimate and last count. The collected data were tabulated and subjected to analysis of variance and then the Tukey test was applied to compare the means.

Soil preparation systems did not statistically influence the average number of days for corn seedling emergence (Table 1), in agreement with what was presented by Magalhães & Durães (2002). Similar observations were verified by Nagahama et al. (2016), where they evaluated the agronomic attributes of forage sorghum subjected to five soil preparation systems and four movement speeds of the mechanized set, in which there was no statistical difference in the speed of seedling emergence.

There was also no statistical difference for the average number of seedlings emerged on the last day of evaluation in each treatment, so it can be deduced that sowing was done homogeneously and effectively. In view of this, there is a similarity with the results of Carvalho Filho et al. (2006), who evaluated the effect of five soil preparation equipment on the development and productivity of soybean crops (Glycinemax L. (Merril)), where there was no statistical difference in the emergence rate of soybean seedlings.

From the data presented in Table 2, it is possible to verify that the conventional soil preparation equipment used did not affect the productivity of corn for silage. Therefore, it is possible to recommend the use of any machine to carry out primary soil preparation. However, as it provides better operational capacity (Silva, 2015), the plow harrow is more recommended for carrying out soil preparation.

The choice of machine and/or agricultural implement used in soil preparation is a point to be observed with caution, as the soil preparation equipment used can cause greater or lesser soil erosion, for example: if there are problems with laminar soil erosion, the plow harrow is not recommended for soil preparation, as the action of the machine promotes greater disturbance of the surface layer of the soil, predisposing it to the risk of erosion.

The soil preparation equipment used in this work did not reduce the emergence speed and productivity of corn silage, when compared with each other (Table 1 and Table 2). This demonstrates that their use promotes adequate soil preparation with good conditions for seeds and plants and, consequently, successful establishment of the crop in the field (Modolo et al., 2011).

The good soil preparation provided by these equipment positively alters the lateral pressures that reach the seeds and, thus, improves seedling emergence (Stout et al., 1961). Furthermore, good soil conditioning stands out as an important factor in establishing the crop in the field (Brown et al., 1996).

Therefore, with the results of this work, it can be concluded that even though different preparation systems were used, there was no influence on the speed of emergence of corn seedlings, the number of plants emerged on the last day analyzed and corn productivity for silage. Therefore, all machines evaluated can be considered effective for soil preparation, given the evaluated variables of corn cultivation, however, it is necessary to consider local conditions and the producer's conditions to correctly choose the equipment to be used.

 

Luiz Fernando Costa Ribeiro Silva; Letícia Almeida; Lucas Oliveiros de Andrade; Alberto Carvalho Filho; UFV