Manejo de nitrogênio em milho para altas produtividades

Criteria for defining nitrogen dose, application timing, and sources in corn crops. If you want to learn more about how to increase nitrogen use efficiency through correct application, doses (kg ha), and sources, keep watching the video and leave your comment below. The goal of a good nitrogen recommendation is to estimate the difference between the nitrogen supplied by the soil and the plant's demand, aiming to achieve high yields and the lowest possible production cost. The plant's nitrogen (N) demand/absorption is around 20-25 kg per ton. Therefore, when we talk about producing 12 t/ha (200 sacks/ha, or almost 500 sacks/alqueire), we are talking about a demand of 250-280 kg of N/ha. Where does this N come from? Part of it comes from the soil (organic matter and cover crops), but the soil cannot meet all the demand to produce 12 t of grain. Therefore, part of it is applied from a mineral source, at the base and as topdressing. How much comes from the soil? The soil's organic matter content is the main variable to consider, based on the logic that for every 1% of organic matter, the soil can release/supply an average of 25 kg of N/ha/year. Let's take an example... soil with 4% organic matter can provide 100 kg of N per year... perhaps 50% of that, or 50 kg for the corn crop. Note that... We're talking about something biological, not mathematical... that is, depending on weather conditions, these values ​​may vary slightly, either higher or lower. [Insert photo of the different cover crops.] A certain amount will be provided by the cover crop... that's why we consider the previous crop, whether it's oats, vetch, turnip, or a mix of plants. We've already discussed in another video how these plants can cycle 50 to 100 kg N ha and this N will be available to the corn subsequently. Observe the dose-response curve data/figures (150 to 180 kg of N). Note that in years with good weather conditions, the response goes a little beyond 150 kg; in bad years, it stays around that. Observe the photo of the N deficiency (on the left without Nitrogen and on the right with 150 kg of N). What we logically observe is an increase in LAI and chlorophyll content. Efficiency of use (kg of corn per kg of urea). Applied), recovery rate (50 to 60%), economic viability. The producer uses (base + topdressing) around 150 to 160 kg of N... or the equivalent of 14-15 bags of urea per hectare to produce 12 t ha (220 bags ha). Criteria to define the dose - Demand x supply Soil capacity to supply N (organic matter content; pre-corn management (cover crop; rotation; legumes); Expected yield (200 bags) Area history (fertility, organic matter, previous productivity, crop conditions (hybrid, plantability, stand, climatic conditions) 2 - The item I want to address is about positioning. How much at the base? How much as topdressing? When to apply? 1 or 2 applications? Look at this figure of the N absorption rate of corn. Note that up to V6 the plant accumulated less than 1 ton of dry matter (DM) or less than 30 kg of nitrogen (N) per hectare. Rapid absorption occurs precisely after V7-V8, because the corn elongates between nodes and rapidly increases its photosynthetic apparatus. At V10, absorption can reach 8-9 kg of N per hectare per day. But you might be wondering, then I don't need to apply much N at the base, because until V6 it absorbs little N. Well, that depends on which preceding crop you have in your area. Notice that in this photo the dynamics will be totally different (oats x turnip), or (oats x vetch). In the situation of corn after oats, which is still the most frequent reality, the demand for N in the corn is greater... Immobilization problem. 50, 70 kg of N may be being immobilized. See this image with oats and turnip... the dynamics improve. How can we manage this? By adjusting the desiccation time, N placement at the base and in topdressing. So, using Formulations with 10 to 12% N can be advantageous. One or two applications as topdressing? ILP (Integrated Crop-Livestock-Forestry) using N in pasture Insert photo of the absorption pattern 3 - Item N Source - Urea vs. protected source The technical and economic viability of using N can vary between nearby crops and between years due to interactions between soil and environmental conditions. Even so, we already have much evidence of its potential use. Association with azzospirillum... cost of 140 reais per liter... application method... furrow vs. seed... environmental conditions... I wish everyone good management and may the rains allow us to obtain high productivity.