<p>Starter fertilizer applied with
or near the seed at planting often enhances early season maize growth (<i>Zea mays</i> L.) but does not always result
in higher grain yield. Other responses to starter fertilizer, such as reduced
thermal time to reach silking, which suggests accelerated plant development,
have been documented. The objective of this study was to examine the relationship
between dry matter production and accelerated plant development with respect to
5x5 cm starter (ST) and in-furrow popup (PU) fertilizer. A field experiment was
conducted in 2016 with three at-planting treatments consisting of one single
rate and formulation of ST (53 N and 21 P kg ha<sup>-1</sup>) or PU (4 N and 6
P kg ha<sup>-1</sup>), and an untreated control. In 2018, the study included
four additional site-years with treatments consisting of an intermediate (ST)
or high (STH) starter fertilizer rate, and an untreated control. For ST
treatments, depending on location, nitrogen (N) and phosphorus (P) fertilizer
rates ranged between 26-28 and 6-10 kg ha<sup>-1</sup>, respectively, and for
STH treatments N and P fertilizer rates ranged between 47-56 and 12-20 kg ha<sup>-1</sup>,
respectively. In 2016, as new leaf collars appeared, dry matter increased
exponentially, but at an equal number of leaf collars ST and PU had similar dry
matter as the control. In 2018, dry matter for ST, STH, and control was also
similar when normalized for leaf collar number at each site. Overall, these
results suggest that enhanced dry matter at a given point in time from ST, STH,
or PU was a function of accelerated leaf development as opposed to physically
more robust plants of the same leaf collar number. Grain yield was unaffected
by ST, STH, or PU treatments at any site-year.</p>
<p>Methods used to study roots in
crop fields have included extracting soil cores, excavating entire root
systems, using radioactive and non-radioactive chemical tracers, or using
mini-rhizotrons. However, due to the intensive nature, level of difficulty, and
cost associated with these methods, their use in crop fields has been minimal.
We developed an alternative method to quantify maize rooting density over time.
The method involved perforated cylinders installed vertically into the soil at
different distances from the row, which made roots growing into the cylinder
voids visible from the soil surface and possible to count [root number density (RND)]
at different depths using a video recording
device (1m-long borescope). The objective of this study was to determine if the
cylinder method could quantify rooting density throughout the growing season
(V3, ~V7, and R2-R3) similar to the more intensive soil core method, compared in two starter fertilizer trials [continuous maize
(M/M) and maize/soybean (M/S) rotation]. Cylinders were constructed with
perforated (49% voids) polypropylene resin to an inside diameter of 2.58 cm and
a length of 30 cm. Cylinders were painted with red and green alternating
markings (5 cm) on the outside and inside walls to visually aid in identifying
depth from the soil surface. After plants emerged, cylinders were inserted
vertically into the soil after drilling a 3.5 cm diameter borehole. Ten
perforated cylinders were installed in a parallel line 13 or 25 cm away from,
and on both sides of, the planted row. Soil cores were also collected at the
same relative locations for conducting root extractions and subsequent
calculation of length density (RLD). At V3, methods frequently resulted in the
same significant (<i>p≤</i>0.10) or
insignificant (<i>p></i>0.10) main and
interaction effects in both fields, whereas at ~V7 and R2-R3, there were
several instances where the cylinder method failed to detect the same effects
as the soil core method. At times both the cylinder method and the soil core
method detected significant main or interaction effects, but the direction of
the effect was opposite.</p>
<p>In-furrow biological (BIO) and
plant growth regulator (PGR) products, otherwise known as biostimulants, are
becoming increasingly available in the commercial maize market. The objective
of this study was to compare the effects of several commercially available
in-furrow biostimulant products on maize growth and development, nutrient
uptake, and grain yield to starter fertilizer in large-plot field trials. The
study was conducted across five locations in 2016, and three locations each in
2017 and 2018 at Purdue University research farms. At each location, treatments
consisted of four different BIO or PGR products plus starter fertilizer,
starter fertilizer only, and an untreated control. Compared to the control,
starter-only increased grain yield at 7 of 8 site-years in 2016 and 2018
ranging from 125 to 753 kg ha<sup>-1</sup>, depending on location, but no
increase was found at any of the 3 locations in 2017. Grain yield was increased
(3 of 11 site-years) or decreased (2 of 11 site-years) by some of the BIO or
PGR products, but in 6 of 11 site-years none of the products affected yield
compared to starter-only.</p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/12268679 |
| Date | 08 May 2020 |
| Creators | Jason Walter Lee (8812097) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/A_COLLECTION_OF_THREE_INDEPENDENT_STUDIES_INVESTIGATING_THE_IMPACT_OF_STARTER_FERTILIZER_ON_MAIZE_GROWTH_DEVELOPMENT_VALIDATING_AN_ALTERNATIVE_ROOT_STUDY_METHOD_AND_TESTING_THE_EFFICACY_OF_BIOSTIMULANTS_IN_MAIZE_PRODUCTION/12268679 |
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