The role of plant functional diversity in an organic intercropping system: Evaluating its effects on soil moisture and temperature dynamics and soil health

Background/Question/Methods

Crop rotations during the heat of Texas’ summers are limited due to the poor availability of crops that can withstand the high temperatures.  Additionally, management practices that enhance or sustain soil and crop productivity while reducing inputs can increase producer profit and reduce the potential for nutrient runoff and leaching.  We are currently investigating different combinations of watermelon, peanut, okra, cowpea and pepper in single crop and various intercropping combinations and their effects on ecosystem services and plant productivity.  Each component crop was selected to perform a specific function within the system.  Specifically, we are assessing the effects of plant functional diversity on soil temperature, soil moisture, and soil health (organic matter content, microbial C and N, total and organic C and N) in a system following strict organic guidelines.  A randomized complete block design with 3 replicates was utilized for this study. 

Results/Conclusions

Although data analysis is ongoing, preliminary observations suggest that intercropping combinations utilizing watermelon reduce soil temperatures and promote short-term soil moisture retention. Temperatures were reduced by between 2 and 3°C on average and short-term soil moisture retention was increase by 25% VWC in these treatments.  Okra benefited most from intercropping when compared to its monocrop with an increase in soil moisture content of 46% VWC.  Contradictory to our hypothesized outcome, preliminary results from soil microbial biomass analysis suggest a decrease in soil microbial C in the intercropping combination of peanut, watermelon and okra as compared to peanut, watermelon and okra grown in monocrop, 701, 940, 955 and 1161 µg C/g dry soil respectively.  There was no significant difference in soil microbial N between the 4 treatments.  We are currently conducting root trait analysis in addition to analyzing other soil chemistry parameters to help explain these observations.  The preliminary information gathered from this investigation has the potential for alleviating heat and soil moisture stress on crops during the peak of the summer heat in Texas.  However, the potential effects of these systems on soil health and nutrient cycling have yet to be conclusively determined from this study.