Corn Nutrition in Río Negro: Optimizing Fertilization for High Yields

The Río Negro valley in northern Patagonia presents a uniquely favorable environment for diverse crop cultivation, with corn consistently featuring in agricultural rotations. Historically grown under irrigation, corn production has expanded in recent decades as land previously dedicated to fruit orchards transitions to more extensive crops like alfalfa and corn, fueled by advancements in sprinkler irrigation technology.

Corn thrives under the edaphoclimatic conditions of the Río Negro valley, but maximizing its yield potential requires a nuanced understanding of its nutritional needs. While nitrogen and phosphorus have traditionally been the primary focus of fertilization strategies, a more comprehensive approach considering macro and micronutrients is crucial. Often, deficiencies in these other essential elements limit nutrient absorption and metabolism, ultimately restricting yield increases.

Modern high-yielding corn hybrids are significant extractors and exporters of nutrients, not all of which are consistently returned to the soil. Efficient and comprehensive nutritional plans are paramount. Despite rapid improvements in corn management practices driven by proactive producers and agricultural professionals, substantial potential remains for further optimization in both productivity and long-term sustainability.

The Chacra Valles Irrigados Norpatagónico (Vinpa) of Aapresid, a collective of producers, has been dedicated to optimizing crop fertilization plans – and other technical aspects – for over a decade. These producers, located in eastern Río Negro and the southern Buenos Aires province, all operate under irrigation and include corn as a key component of their rotations.

Fertilization in Corn: Nitrogen, a Key Nutrient

Nitrogen is typically the most heavily emphasized nutrient in corn cultivation due to its high demand and significant impact on production costs. However, effective nitrogen management extends beyond simple application. Factors such as target yield, application timing, nutrient availability delays, nitrate leaching into groundwater, and nitrogen loss through atmospheric processes (particularly in flooded conditions) must be carefully considered. The initial availability of nitrogen from soil mineralization is often overlooked in current planning.

“The use of leguminous service crops can replace up to 100 kg N.ha-1 of fertilizer.”Alfonso Cerrotta, RTD Vinpa Chakra (Aapresid)

Integrating leguminous service crops offers a promising avenue for supplementing nitrogen supply. Studies at Chacra Vinpa demonstrate that these crops can potentially replace up to 100 kg N.ha-1 of synthetic fertilizer, alongside providing other valuable ecosystem services that often offset implementation costs. The gradual release of nitrogen from decomposing biomass also reduces the risk of losses due to leaching or runoff. Nitrogen-fixing microorganisms can complement mineral fertilization, offering a favorable cost-benefit ratio.

Fertilization in Corn: Other Important Nutrients

Phosphorus is another nutrient routinely applied to cornfields in the valley. While current practices often meet or exceed phosphorus extraction rates, its availability is influenced by soil pH and the presence of cations like calcium and sodium, which can render it inaccessible to plants. Although research at Chacra Vinpa hasn’t shown yield responses to phosphorus additions beyond replacement levels, it’s hypothesized that the alkaline and calcareous nature of the soils reduces phosphorus availability, necessitating acidic sources of the nutrient and nitrogen fertilizers that modify soil pH.

Zinc is a micronutrient consistently found to be deficient in valley soils and should be included in all corn fertilization plans. Early application of at least 0.5-1 kg of zinc per hectare is recommended. Studies at Chacra Vinpa have shown yield increases exceeding 1000 kg.ha-1 with the application of solid zinc products as a starter fertilizer.

As nutrient extraction continues without adequate replacement, deficiencies in other micronutrients – iron, boron, copper, and manganese – and macronutrients like potassium and sulfur are likely to emerge. Foliar applications of micronutrients and some macronutrients have demonstrated yield responses exceeding 10% in Farm trials, indicating a high cost-benefit ratio as a complement to basic fertilization.

while simplified fertilization approaches focusing on one or two primary nutrients are common, a more holistic strategy is essential. A robust fertilization plan begins with incorporating rotations, preferably with leguminous cover or service crops, followed by accurate soil analysis at planting, conducted with the guidance of an agricultural professional. The selection of fertilizers should then align with their chemical characteristics and the irrigation method employed, with precise timing and dosage for each source. Finally, monitoring for deficiency symptoms during the growing season or conducting leaf analysis can inform corrective measures for the current crop or guide planning for the subsequent season.

Alfonso Cerrotta, RTD Chakra Vinpa (Aapresid).