Date of Award
Master of Science
Antonio P. Mallarino
Use of fluid N–P or N–P–K starter mixtures in most research studies precludes firm conclusions about specific starter K effects on early crop growth and grain yield. This study evaluated corn (Zea mays L.) early growth, early plant K concentration and uptake, and grain yield response to fluid starter K fertilizer. Eight trials were conducted during 2007 and 2008 in Iowa farmers’ fields using a strip trial methodology, global positioning systems, yield monitors, and geographical information systems. Six sites were managed with chisel–plow tillage and two with no–tillage. Soil–test K (STK) was measured using a dense grid sampling approach (0.13–to 0.4–ha cells). Treatments replicated three times were a control, commercial fluid K2CO3 starter (0–0–25 N–P–K) applied in the seed furrow at 14 to 21 kg K ha−1, broadcast K at 112 kg K ha−1, and broadcast K plus starter K. Means from the entire length of the strips showed that K fertilization did not affect early plant dry weight (DW) or K uptake consistently, but increased K concentration at most sites and increased grain yield at three sites. At two sites broadcast K increased yield more than starter K, and at one site both fertilizers increased yield similarly. Sites with plant DW or K uptake responses did not show a yield response. Starter K in addition to broadcast K did not increase yield further. Analyses of plant measurements by soil series or areas with STK in various STK interpretation classes for each field did not show consistent differences in responses to starter or broadcast K. Overall, the results showed that starter K seldom increased early corn DW or K uptake and the infrequent increases seldom resulted in increased grain yield. Starter K applied in addition to broadcast K rates commonly applied by farmers did not increased yield further.
Bergmann, Nicolas, "On-farm evaluation of fluid starter potassium fertilization for corn using precision agriculture technologies" (2009). Graduate Theses and Dissertations. 11052.