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

View the project report

Commodities

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

Practices

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

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.