Sign up for email alerts of new Fluid Journal issues!
Fluid Journal : Fall 2013
14 The Fluid Journal Fall 2013 as needed during the growing season. Rates. Corn N fertilizer rates varied from 150 to 250 lbs/A, depending on the site. Plot size was 30 or 50 feet in length and 10 or 15 feet in width, with row-spacing of 30 inches, except for soybean row spacing, which was 15 inches at one site. Design. The experimental design was a factorial arrangement in a randomized complete block design with three replications. Fertilizers. The starter fertilizer factor consisted of three treatments: control, NPK, and NPK plus a micronutrient blend of Fe, Mn, Zn, Cu, and B (referred to hereafter as NPKM). Rates were 4, 10, and 10 lbs/A of N, P2O5 and K2O. Starter fertilizer was surface dribbled over the row. The foliar fertilizer factor consisted of the same three treatments: control, NPK, and NPKM. The factorial arrangement resulted in nine combinations between starter and foliar treatments. The foliar fertilizer was applied at the V6-V8 corn growth stage and at the R2 soybean growth stage. The rates were 2, 2, and 2 lbs/A of N, P2O5 and K2O using a 10-10-10 (N-P2O5-K2O) fertilizer formulation. Foliar fertilizer was applied using a CO2 pressurized backpack sprayer adjusted to 0.134 MPa and diluted into 20 gal/A of water. Micronutrients. The micronutrient mix contained B derived from boric acid, CuEDTA (ethylenediamine tetraacetic acid), MnEDTA, ZnEDTA, and FeHEDTA (N-hydroxyethyl-ethylenediamine triacetic acid) at rates of 0.5 lbs/A for each micronutrient. The foliar micronutrient blend contained the same products used for starter at rates of 0.2 lbs/A for each micronutrient. Soil samples. Composite soil samples were collected from each small plot from the 0- to 6-inch depth prior to planting. Soils were oven dried, crushed to pass through a 2 mm sieve. Soil samples were analyzed for pH (1:1 soil water), P by Mehlich-3 colorimetric method, K by ammonium acetate, organic matter (OM) by weight loss on ignition or Walkley-Black method, cation exchange capacity (CEC) by summation, Fe, Mn, Zn, and Cu by DTPA, and B by hot water. Plant samples consisted of five or ten above-ground whole corn plants collected near the V6 growth stages from each small plant prior to foliar application. Plant samples for soybeans consisted of 30 of the uppermost fully-expanded trifoliolate leaves without petioles at the R2 growth stage from each small plot prior to the foliar fertilizer treatment. Plant analysis. Plant samples were Figure 3. Effect of starter fertilizer application on corn grain yield. Letters indicate statistically significant difference between treatments at p ≤ 0.05 Figure 4. Corn grain yield response for one responsive location in 2012 (Rossville). This location was sandy with low organic matter content. Letters indicates statistically significant difference. ovendriedat65oCfor3to5days, weighed, and ground to pass a 2mm screen. After digesting with HNO3 and 30 percent H2O2, the concentration in plant samples for P, K, Ca, Mg, S, Cu, Fe, Mn, Zn, and B was determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES). Total N for plant samples was determined by dry combustion, using a LECO FP-528 Nitrogen Analyzer. Plant height. Soybean plant height was recorded at full maturity (R8 growth stage). Grain yield was determined from the center 2 or 4 rows of each small plot and adjusted to 13 and 15.5% moisture for soybeans and corn, respectively. Data were analyzed with the MIXED procedure in SAS 9.2 (SAS Institute) with blocks as a random factor. For analysis across sites, both site-year and block within site-year were considered as random factors. Statistical significance was determined at p = 0.10.
Late Spring 2013