Document Type
Dissertation - Open Access
Award Date
2024
Degree Name
Doctor of Philosophy (PhD)
Department / School
Agronomy, Horticulture, and Plant Science
First Advisor
Peter Kovacs
Abstract
Cold and wet spring conditions during planting in the Northern Corn Belt can limit nutrient mobility, especially phosphorus (P) due to reduced mineralization. This often triggers the use of starter fertilizers to enhance nutrient availability within the root zone, and as a result improve nutrient uptake and the overall plant growth. Albeit research has shown that starter fertilizer applications can significantly boost corn grain yield potential, the most substantial yield responses from starter fertilization are typically observed in fields where soil test P levels fall below the critical soil test P threshold. This dissertation explores i) the effects of starter fertilizer placement on corn development, nutrient uptake, and grain yield as affected by planting dates in phosphorus-sufficient soils in eastern South Dakota (SD) across multiple environments, and ii) the impacts corn seedling emergence on plant-to-plant grain yield variability as affected by starter fertilizer placement. Field experiments for the first study were conducted from 2021 to 2023 at three locations in eastern SD. The treatments included early and normal planting dates with varying starter fertilizer combinations, placements, and rates. The liquid starter fertilizers (10-34-0 and 8-21-5) were applied with and without additional zinc and were placed in the seed furrow at a lower rate (IFL) and a higher rate (IFH), 5cm to the side and 5cm below the seed normal rate placement (5x5), a combination of IFL and 5x5 placement (Combo), and an untreated control with no starter fertilizer application (UTC). The IFL, IFH, 5x5, and Combo treatments provided 10, 15, 25, and 35 kg P2O5 ha-1 respectively, irrespective of starter fertilizer sources. Pre-plant urea was applied to balance the nitrogen fertilizer requirement of the corn plants regardless of the starter fertilizer treatment at a rate of 168 kg N ha-1. Planting dates did not influence corn response to starter fertilizer placement across the locations. Starter fertilizer placement increased early-season leaf appearance (growth stage), plant height, dry matter production, and nutrient uptake compared to the control (UTC), though these improvements did not translate into increased whole-season crop physiological parameters or grain yield. Results suggest that starter fertilizer applications will not be needed for grain yield improvement in P-sufficient soils under the conditions of this study. Field experiments for the second study were conducted in Brookings, SD, during the 2022 and 2023 growing seasons, using the same planting dates and starter fertilizer treatments described above. The temporal and spatial variability of seedling emergence was examined in relation to starter fertilizer placement and planting timing. Results indicated that starter fertilizer placement had minimal influence on the timing of seedling emergence across both planting dates in both years. Late-emerging corn was more closely associated with environmental stressors, such as soil temperature and moisture content. Delays in corn developmental stages, reduced final plant height, and lower per-plant grain yield were linked to late-emerging plants; nevertheless, the most critical factors influencing final yield outcomes were silk emergence timing, final plant height, and plant spacing with R² values ranging from 0.04 to 0.43. Although seedling emergence was not found to be the most influential factor in reducing corn grain yield, minimizing conditions that delay emergence remains essential, due to their potential impacts crop growth parameters that could eventually impair corn grain yield.
Publisher
South Dakota State University
Recommended Citation
Dorissant, Larousse, "Impacts of Starter Fertilizer on Corn Development, Nutrient Uptake and Grain Yield in Eastern South Dakota" (2024). Electronic Theses and Dissertations. 1332.
https://openprairie.sdstate.edu/etd2/1332