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Corn grain yield response to sulfur fertilization in IndianaDiana Salguero (11211201) 01 September 2021 (has links)
Reduction in sulfur deposition from power plant
emissions has resulted in lower amounts of soil sulfur and, perhaps, in
inadequate sulfur availability for corn. The objective of this study was to
determine if corn (<i>Zea mays</i> L.) grain yield was responsive to S
fertilization in Indiana and what soil and cropping system factors contributed
to the likelihood of a response. Field scale experiments were conducted at 28
sites from 2017 to 2020, the majority in corn-soybean (<i>Glycine max</i> (L.)
Merr) rotation. In-season measurements included soil sulfate-S concentration
and soil texture from 0 to 60 cm in 20 cm increments, plant nutrient
concentration in the whole plant at V3-V7, in the earleaf, and in the grain.
Additional measurements were 1,000 kernel dry weight, total kernel rows per
ear, and kernels per row. Sulfur treatment rates ranged from 0 to 34 kg S ha<sup>‑1</sup>
as ammonium thiosulfate, and were applied as starter, sidedress, and both
combined. Fertilizer S increased grain yield by 0.2 to 3.0 Mg ha<sup>-1</sup>
at 10 of 28 Indiana site-years, approximately a 36% frequency of response. When
a response to S fertilizer occurred, the lowest sidedress rate examined in that
site-year, which ranged from 8 to 17 kg S ha<sup>-1</sup>,<sup> </sup>was
enough to maximize grain yield. On soils with 26 to 31 g kg<sup>-1</sup> OM, S
fertilization increased yield 0.2 to 0.3 Mg ha<sup>-1</sup> at 2 of 10
site-years. Response to S fertilization at 8 of 10 site-years with soils with
lower OM, 10 to 25 g kg<sup>-1</sup>, had higher yield increases ranging from
0.7 to 3.0 Mg ha<sup>-1</sup>. Grain yield responses occurred in both coarse-
and fine-textured soils and were consistent and large at 2 sites. Sulfate-S
concentration in the soil and S concentration in the whole plant (V4-V7) were
not good indicators of response to S fertilization. For the majority of the site-years
where grain yield increased with S fertilization, the grain S concentration,
earleaf S concentration, and earleaf N:S were respectively <0.9 g kg<sup>-1</sup>,
<1.8 g kg<sup>-1</sup>, and >15:1 without S treatment. These parameters
improved with the addition of S but some site-years with these values did not
have a yield response. These earleaf S and N:S ‘critical values’ may serve as
reference for potentially S responsive sites, but more observations are
necessary to validate these critical levels. Sites with higher basal values
(without fertilizer treatment) for earleaf and grain S concentration and lower
earleaf N:S still showed increased tissue S concentration upon S fertilizer
application, albeit with no increase in grain yield. We encourage farmers to
consider S fertilization at rates ranging from 8 to 17 kg S ha<sup>-1</sup>
applied at sidedress. this recommendation for fields showing S deficiency
symptoms or where R1 earleaf S concentration and N:S are below 1.8 g kg<sup>-1</sup>
and above 15:1, respectively.
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INVESTIGATION OF CORN YIELD IMPROVEMENT FOLLOWING CEREAL RYE USING STARTER NITROGEN FERTILIZERHouston L Miller (7830965) 20 November 2019 (has links)
Cereal rye (CR), the most common and effective nitrogen (N) scavenging
cover crop option in the Midwest, is often utilized in cropping systems to
reduce nitrate loss for environmental benefits. To increase environmental
efficiency in Midwest corn cropping systems, we must increase the overall
adoption of CR. However, due to the yield reduction potential (6%) for corn
planted after CR termination, CR is primarily recommended before soybean. To
increase CR adoption, we must develop adaptive fertilizer management practices
that achieve competitive grain yields relative to cropping systems where CR is
not adopted. Therefore, the objectives of this study are to determine (1) the
effect of CR and starter nitrogen rate on corn growth and nitrogen content. (2)
the optimum starter nitrogen rate to achieve agronomic optimum corn yield
following CR. (3) the impact of phosphorus (P) at starter on plant growth,
nitrogen content, and yield with the inclusion of CR. For our study, five
starter N rates were applied in a 5x5 cm band to both CR and non-CR plots,
concentrations ranged from 0-84 kg N ha<sup>-1 </sup>in 28 kg N ha<sup>-1</sup>
intervals. Total N applied was the same for each treatment, relative to its
location, and was split between starter N at planting and sidedress applied at
growth stage V6 relatively. Although CR termination took place at least two
weeks before planting, CR decreased corn grain yield at one of three locations
by an average of 8%, nitrogen recovery efficiency (NRE) by 27%, and R6 total N content
by 23%, relative to the conventional control (non-CR 0N), when no starter N was
applied. At one of three locations, starter N rates of 56 kg N ha<sup>-1</sup>,
56 kg N ha<sup>-1 </sup>plus 17 kg P ha<sup>-1</sup>, and 84 kg N ha<sup>-1</sup>
increased corn grain yield, in CR plots, and 56 kg N ha<sup>-1</sup> plus 17 kg
P ha<sup>-1</sup> increased corn grain yield in non-CR plots. Phosphorus increased
corn grain N content at growth stage R6 in one of three locations and did not
impact corn grain yield at all locations. We conclude that the inclusion of
starter N at planting has the potential to increase agronomic productivity in
CR corn cropping systems in soil environments with a high capacity to
mineralize soil N. However, further research is required to refine our starter
N results to find an optimum starter N rate to apply before planting corn
following CR.
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