Developing climate resilient cropping systems: Investigating how increasing temperatures and crop management influence forage quality

Commodities

• Agronomic: grass (misc. perennial), medics/alfalfa

Practices

• Animal Production: feed/forage
• Crop Production: varieties and cultivars, other

Forage growers in Pennsylvania and the northeastern US are facing
challenges due to climate change and may need to adapt management
practice to mitigate climate risks on forage productivity and
quality. Knowledge on how crop management practices will perform,
both in terms of productivity and quality, under future climatic
conditions will allow us to identify climate resilient management
practices. To address this knowledge gap, we will conduct a field
experiment examining how forage management practices (harvest
frequency and alfalfa variety) under normal or elevated
temperatures affect forage quality. Specifically, we will examine
how warmer temperatures and forage management affect protein and
fiber concentrations within forage tissue at critical harvest
timepoints likely to be responsible to both temperature and
management. We will use open-top chambers to increase temperature
within the field. We will also examine the effects of management
on forage productivity, but that is outside the scope of this
proposal. Maintaining forage quality is important because of its
economic significance to forage growers and dairy farmers. This
analysis will enable us to understand the dynamics of
environmental effects on forage quality and make better
recommendations to the farmers about how to maintain forage
quality in response to environmental variation. We plan to
disseminate our results through different scientific and
extension presentations and publications.

Objective 1

To quantify the effects of forage management (harvest frequency
and alfalfa fall dormancy levels) and temperature (ambient and
warming) on forage quality at different harvest time points in an
alfalfa and orchardgrass mixture.

Hypothesis 1: More frequent harvests and the
alfalfa variety with lower fall dormancy (FD5) will produce
higher protein (CP) and lower fiber (NDF, ADF, and ADL) content
(a better quality) in alfalfa and orchardgrass under warmer
growing conditions compared to ambient temperature. Warmer
temperatures are usually reported to decrease forage quality, but
we predict that increased temperature combined with five harvests
per year will have increased forage quality compared to when five
harvests per year is combined with ambient temperature. In
contrast, we predict that the four harvests per year and higher
fall dormancy (FD4) variety will have increased forage quality
under ambient compared to warmer temperatures.

Hypothesis 2: More frequent harvests will result
in better forage quality for orchardgrass under warmer growing
conditions.

Objective 2

Determine to what extent, environmental factors (including soil
and air temperatures, and growing degree days (GDD)
measured/calculated at plot level) predict forage quality, and
whether this varies between different harvest time points.

Hypothesis 1: Higher temperatures and GDD
accumulation will be associated with higher fiber content and
lower protein content (a poorer quality) in both alfalfa and
orchardgrass.