Delaware Agronomy Blog

University of Delaware Cooperative Extension

Category: Planting (page 1 of 2)

Corn planting timing effects on yield and the relationship to deer feeding

Figure 1: Deer being allowed to eat our plots because it was part of the research.

Based on some observations in prior years, we planted irrigated corn on three different timings (April, May, and June) to observe three outcomes 1) yield, 2) nutrient uptake, 3) herbivory by deer. Average yields were all below 200 bushels, at 143, 175, and 128 bu/acre in the April, May, and June planted plots, respectively. Yield losses are potentially related to a range of factors, including deer feeding, weather, and soil nitrogen.

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Fall Establishment of Small Grains for Tillers

Proper establishment of small grains will ensure success when springtime temperatures begin to warm. Some practices that help with planting include germination tests, tillage (after corn), and planting during the optimal window (https://sites.udel.edu/weeklycropupdate/?p=12483). When considering planting rates, research at UD has not seen increased yields above 1.5 million seeds per acre (https://sites.udel.edu/agronomy/2020/10/01/2018-2020-wheat-seeding-rate-yields/). This follows many regional recommendations, but without good seed to soil contact, moisture, or N, you may still have a slow start.

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2022-2023 Cover Crop Growth and Tillage

For all crops, initial establishment is as important as fertility in maximum yield. The same principles adhere to cover crop growth, with earlier establishment and good seed to soil contact necessary for good coverage.

Figure 1: Fields in March 2023 of a) turbo tilled rye cover crop after rainfed corn, b) no-till broadcast rye after irrigated corn, c) flown on after full-season + double crop soybeans and d) turbo-tilled rye after irrigated corn.
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Soybean Yield Response to Planting Populations, Row Spacing and Irrigation

To update our recommendations for soybean population, the Delaware Soybean Board sponsored a study of five different planting populations (60, 90, 120, 150, and180,000 seeds per acre), two row spacings (15 and 30”), and included irrigated and rainfed treatments under variable rate irrigation. Overall, no differences in yield were observed by population, while 15″ rows boosted yields by 10.6 bushels and irrigation boosted yields by 25.9 bushels.

Figure 1: a) aerial image of planting populations and row spacings at our Irrigation research farm, b) rainfed plots senescing earlier under our variable rate linear irrigation field.

Project Summary

Soybeans (maturity group 4.3) were planted at the UD Warrington Irrigation Research farm in May 2022 and harvested in November 2022 with a plot combine. The results were analyzed statistically as a randomized complete block design with three factors (population*row-spacing*irrigation) with means separation by Fisher’s LDS (alpha = 0.1).

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A Warmer 2021 is Boosting Emergence

Emerging corn in a rye cover crop

Emerging corn in a rye cover crop

While it may not seem much warmer than it was in 2020, having steady days above 50°F had provided much faster emergence than last year. In 2019 we were getting about 10 growing degree days (GDD) per day, while now we are seeing 15-20. The threshold for emergence is about 100-120 GDD, which we have reached for most fields planted between April 15 and April 22nd (Table 1). In 2020, we had only reached half of that (60-90 statewide) over the same time period.

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