Soil microbial community composition in a peach orchard under different irrigation methods and postharvest deficit irrigation

Authors: DANGI, SAKIKSHYA - University Of California; Zhang, Huihui; Wang, Dong; Gerik, James; HANSON, BRADLEY - University Of California

Submitted to: Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/2/2016
Publication Date: 5/16/2016
Citation: Dangi, S.R., Zhang, H., Wang, D., Gerik, J.S., Hanson, B. 2016. Soil microbial community composition in a peach orchard under different irrigation methods and postharvest deficit irrigation. Soil Science. 181:208-215. doi: 10.1097/SS.0000000000000153.

Interpretive Summary: Deficit irrigation is a management practice where plants receive less than full irrigation but only at certain growth stages in order to minimize yield loss or long-term impacts to the crop while conserving water. Deficit irrigation can be successfully used in peach production, especially after harvest, but it is unknown how deficit irrigation effects soil microbial communities. Soil microorganisms have important roles in soil structure formation, nutrient cycling, litter decomposition, and overall soil quality, so it is important to know the effects of deficit irrigation treatment on soil microbial communities. Deficit irrigation did not affect microbial community biomass or structure; however, irrigation method (furrow, micro-sprinkler, and surface drip) affected the microbial community biomass and structure in the upper 5 cm of the soil profile while conserving water. The findings are useful for land management and to land owners because soil microbial communities play a significant role in nutrient cycling and crop production.

Technical Abstract: The San Joaquin Valley (SJV) is California’s top agricultural region, cultivating more than 250 unique crops and much of the nation’s fruits, vegetable, and nuts. One of the main limiting factors for production in this region is the reduced availability of water. Deficit irrigation is a management practice where plants receive less than full irrigation but only at certain growth stages in order to minimize yield loss or long-term impacts to the crop. Managed deficit irrigation could be used to help reduce the impact of water shortages in the SJV and has been studied for perennial cropping systems such as trees and vines and in some cases can actually be beneficial to crops. As soil microorganisms have important roles in soil structure formation, nutrient cycling, litter decomposition and overall soil quality, it is important to know the effects of deficit irrigation treatment on soil microbial communities. In the present study, full- and deficit irrigation treatments were applied for seven years using furrow, micro-sprinkler, and surface drip irrigation systems in a peach orchard. In the seventh year of the irrigation study, soil samples were collected before and after implementation of the deficit irrigation treatments to investigate the effects on soil microbial community biomass and composition. Results showed that microbial community biomass and composition were not affected by deficit irrigation treatment when compared to full irrigation. However, different irrigation methods used in the study significantly affected the concentration of soil microbial biomass, Gram + bacteria, Gram – bacteria, fungi and arbuscular mycorrhizal fungi (AMF) for surface soils. Soils at the surface remained dry for longer periods under furrow irrigation where irrigation was less frequent than the micro-sprinkler and drip irrigation methods. Fungal and AMF PLFAs were significantly higher in micro-sprinkler and drip irrigation methods as compared to furrow. The findings are useful for land management and to land owners because soil microbial communities play a significant role in nutrient cycling and crop production.