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Fluid Journal : Winter 2015
8 The Fluid Journal Winter 2015 to slightly over 5,200 feet. Trials. On-farm trials were established using cooperator field equipment and management practices, or management suggestions offered by DuPont Pioneer sales professionals. Production practices and certain environmental details, important for corn development, were recorded by DuPont Pioneer sales representatives, field agronomists, and account managers in fields where test plots were planted (Table 1). Harvesting. Strips were harvested with cooperator or custom harvester equipment. Corn grain from each strip was weighed using a weigh wagon. These data were recorded and archived in computer programs and in written form for comparison following harvest. Hybrids. Yield comparisons among hybrids and management practices were made to identify a hybrid or trend in a practice(s) that may improve on-farm production or efficiencies in management practices. Trends identified as practices that may enhance production were applied to multiple fields to determine the reproducibility of the plot data. Results Management practice revisions by Texas, Oklahoma Panhandle, Southwest Colorado, and northern New Mexico irrigated corn farmers have demonstrated the value of processes already discussed. Banding nutrients is better than broadcasting for positional availability in strip-till and no-till. For example, numerous demonstrations comparing tillage practices have shown improved corn yield with strip-till and no-till, compared to conventional tillage. The value of reduced tillage was enhanced during periods of drought and limited availability of irrigation water owing to declining aquifer levels or state mandated water allocations. Furthermore, these programs display soil moisture preservation, reduced soil erosion by wind, reduced soil compaction, plus aids in water filtration by leaving residue on the soil surface. Starter fertilizer. Producers were taught (in clinics) about the importance of starter fertilizer as a component of high-yield corn, especially in strip-till and no-till systems where soils warm slowly when covered by residue. On-farm test plot evaluations were made for surface banding starter fertilizer two inches from the seed slice (2x0 placement). The results of this study and educational efforts have increased the usage of 2x0 starter fertilizer among High Plains corn producers. Combinations of pop-up and 2x2 or 2x0 are best or pop-up and a "hot" band 6 to 8 inches below the seed applied preplant, especially in no-till or strip-till or early planting in cold wet soils. These efforts have illustrated the ease of application and low set-up costs, compared with traditional 2x2 starter fertilizer placement. Another benefit of the 2x0 practice was that wet soils did not affect starter fertilizer placement that typically hampered traditional fertilizer coulters during planting. Precision guidance systems have made possible the latest fertilizer trend among growers. This program involves banding preplant fertilizer 8 to 10 inches deep during strip-till, followed by planting over the band and using in-furrow pop-up starter fertilizer to achieve the highest yields. Nitrogen. Multiple applications of N are more efficient and result in higher yields (preplant, starter, pre- tassel applications through pivot or sidedress, and post-tassel applications). N rates of 1.2 to 1.3 lbs per bushel of grain, used by many soil testing labs, remain a standard when 100 percent of the N is applied prior to planting the crop. However, the International Plant Nutrition Institute (IPNI) has emphasized the interconnectedness of the 4Rs of nutrient stewardship and how rate, time, source, and placement of fertilizer are interdependent. Thus, N rate can be adjusted based on timing and placement without affecting grain yield. Our test plot data confirm this (Table 2). Growers, who apply a portion of their N preplant followed by starter, sidedress, or via pivot at V4 to V6 stage, along with R2 to R4 stage N application via center pivot, were able to produce a bushel of grain with 0.8 lbs of N. This practice can increase producer profitability because it allows adjustment of N rates based on in-season price fluctuations of N fertilizer, corn, or growing conditions. For example, high corn yields may not be possible for producers with limited available irrigation water in the absence of favorable growing conditions and precipitation. These growers can be conservative with fertilizer inputs and make in-season adjustments of N rates when growing conditions favor increased potential for grain yield. This practice also allows producers to reduce or eliminate N application following a catastrophic weather event, such as hail. Furthermore, single high-rate application of N increases the probability of stalk rot when environmental conditions favor these diseases. Multiple application of N fertilizers through the season helps Table 1. Variables Recorded for On-Farm Test Plots Planting Date Fertilizer Rate Seeding Rate Fertilizer Placement Irrigation Capacity Fertilizer Timing Irrigation Water Applied Fertilizer Products (inches/acre) Previous crop Precipation (inches) Tillage Practices High and Low Daily Temperature Herbicide (Product and Timing) Elevation Fungicide (Applied or not Applied) Soil Type Insecticides Soil Fertility Tests (Plot) Miticides Table 2. N Rate Adjustments Based on Timing and Method of Application N Application Timing and Method N Rate to Produce a Bushel of Corn 100% Pre-Plant Broadcast 1.3 lbs 100% Pre-Plant Band 1.2 lbs 100% Fertigation 1.1 lbs 50% Pre-Plant and 50% Side-Dress 1.0 lbs Pre-Plant/Starter/Side-Dress 0.9 lbs Pre-Plant/Starter/Side-Dress/Fertigation/Post-Tassel 0.8 lbs