Agriculture Reference
In-Depth Information
It must be noted that spring wheat plant N content, grain N content,
plant biomass, or grain yield were never different between the CRN-con-
trol and the CR-control (Figures 2 and 3). It therefore appears that suf-
fi cient soil N was available for crop production subsequent to broccoli
crop residue incorporation, regardless of pre-plant fertilizer application
for spring wheat. Thus, growers may be able to reduce N fertilizer applica-
tions to spring wheat planting, following broccoli production because the
mineralization of crop residue may provide suffi cient SMN.
Relative to the CR-control, the treatments which indicated a detri-
mental effect on spring wheat production were the OCA-straw and CC-
oat, based on a lower spring wheat plant N content, grain N content,
plant biomass, and grain yield, compared to the CR-control or CRN-
control (Figures 2 and 3). Also, the CR-removal treatment indicated a
reduction in spring wheat plant biomass and grain yield compared to
the CR-control or CRN-control in 2010 (Figures 2 and 3). Conversely,
the OCA-yard and OCA-oil treatments did not have different plant N
content, grain N content, plant biomass, and grain yield, compared to
the CR-control or CRN-control (Figures 2 and 3). Therefore, it appears
that the OCA-yard or OCA-oil treatments after broccoli harvest did not
negatively impact the subsequent spring wheat production, but the OCA-
straw, CC-oat, and CC-removal treatments resulted in spring wheat yield
penalties.
It is possible that N supply was suffi cient for spring wheat produc-
tion in the CR-control, CRN-control, OCA-yard, and OCA-oil treatments.
To optimize N use effi ciency, early-season N availability has been rec-
ommended to achieve a desired spring wheat yield goal, rather than late-
season N availability [27]. If early-season SMN levels were limiting for
plant production, decreased vegetative dry matter accumulation and grain
yield may occur [27]. Thus, the rate and timing of OCA and its decompo-
sition is crucial for determining N dynamics. The grain yield results sug-
gested that N supply was suffi cient for the spring wheat growing season
after the OCA-yard and OCA-oil, but perhaps not the OCA-straw (Figure
3). Likewise, the CC-oat and CR-removal treatments may not have had
suffi cient available N (Figure 3). Thus, N fertilizer applications may be
required to maintain the spring wheat yield after OCA-straw, CC-oat, and
CR-removal practices.
