Performing Department
(N/A)
Non Technical Summary
A key component of managing crops to withstand environmental stress is optimizing beneficial plant-microbe interactions that improve water and nutrient availability to plants and deter pathogens. Strategies to achieve this include use of cover crops to stabilize soil and sustain diverse soil microbial communities, and addition of compost to supplement carbon and nutrients and improve soil properties. Benefits from these strategies are slow to emerge in hot, semi-arid environments such as the Texas Southern High Plains (SHP), the leading cotton production area in the U.S. where crop and biological activities are limited by water and nutrient availability, discouraging growers from investing in these practices. We also know little about soil microbiomes and how they are involved in crop response to drought and pathogens in these already stressful environments. To address this gap, this project will 1) Identify changes in soil microbiomes and cotton productivity in response to cover cropping and compost applications across two soil types, 2) Quantify how these treatments affect the resistance and resilience of key microbial functions to severe drought, and 3) Quantify how these treatments affect soil suppressiveness to a cotton pathogen. These results will reveal the combined and individual effects of cover cropping and compost additions on soil microbiomes and cotton productivity across soil types, as well as better define the role of soil microbes in cotton response to drought and pathogens.
Animal Health Component
70%
Research Effort Categories
Basic
30%
Applied
70%
Developmental
0%
Goals / Objectives
The overall goal of this project is to determine how cover crops and compost application in semi-arid cotton systems alters soil microbiomes and the ability of cotton plants to resist drought (abiotic) and pathogen (biotic) stress.The major specific goals of this project are to 1) Identify changes in soil microbiomes and cotton productivity in response to cover cropping and compost applications, 2) Quantify how cover cropping and compost application affects the resistance and resilience of soil microbiomes and cotton growth to severe drought, and 3) Quantify how cover cropping and compost addition affects soil suppressiveness to a widespread cotton pathogen, Verticillium dahliae.
Project Methods
The overall approach for this project includes:•Establish multi-year field experiment with factorial compost and cover crop treatments in semi-arid cotton•Measure soil properties, identify soil microbiome from field experiment•Assay soil microbiome and cotton response to drought, pathogen stress after two years of field treatmentsThe methods used for each objective are briefly described below:1. Field study:Establish a field study with a randomized complete block design (6 blocks) at the TTU New Deal Research farm. Each block contains a factorial combination of the following: 1) Annual application of composted cattle manure (+Compost), 2) Cover crop mix of wheat and field pea (+Cover), 3) combined compost and cover crop addition (+Compost +Cover), or 4) no treatment (Control).Compost treatment consists of composted cattle manure obtained locally that is surface-applied to treated plots at a rate of 20 Mg ha-1.Cover crop treatment consists of a mix of winter wheat (Triticum aestivum L.) and field pea (Pisum sativum L.) planted each year following cotton harvest and terminated prior to cotton planting.Soil and cotton root-associated (rhizosphere) samples will be collected from field treatments twice each year and monitored for soil biological, physical, and chemical responses to management, including microbiome analysis using next-generation amplicon sequencing for bacterial and fungal community composition.Measurements include: soil pH and EC, soil NH4+ and NO3− , permanganate-oxidizable carbon (POX-C), total soil organic matter (SOM), soil organic carbon (SOC) and total nitrogen (TN), routine soil test nutrients (P, K, Ca, Mg, Cu, Na, S, Zn), bulk density and mean weight diameter/size distribution of soil aggregates, available water holding capacity and infiltration rates. Biological indicator measurements include soil microbiome analyses for bacterial and fungal community composition, soil microbial biomass carbon (via chloroform fumigation-extractions), and extracellular enzyme activities related to C, N, and P cycling.2. Drought challenge studyCollect soils from experimental field plots after two full years of treatment application, and apply severe drought conditions to field-collected soils in a greenhouse setting and measure the response of soil microbiomes, microbial functions, and cotton growth.After the first open flower has been observed in cotton planted in duplicate greenhouse pots containing soils from each field treatment (described in Objective 1), the pots from each field treatment plot will be divided and subjected to either Drought or No Drought conditions, where pots will be 1) watered at regular intervals at a rate of approximately 5 mm day-1 for the next 15 days (No Drought), or 2) water will be withheld for the next 15 days (Drought).Measured parameters on soils after drought experiment will be the same as in Objective 1, with additional measurements of plant biomass (root and shoot mass) and productivity (e.g., boll count).3. Pathogen challenge studyCollect soils from experimental field plots after two full years of treatment application, and challenge soils from each field treatment by inoculation with Verticillium dahliae in controlled greenhouse conditions.Duplicate greenhouse pots containing soil collected from each field treatment as described for Objective 1.Soils for each treatment will be infested with 200 microsclerotia/g soil of Verticillium dahliae and poured into a PVC tube at the center of the pot, which will then be pulled from the pot, leaving the center infested with V. dahliae (Vd). Cotton seeds (5) will be planted in the center area which has the V. dahliae microsclerotia. Plant and soil measurements will be the same as described for Objective 2, with additional soil samples assayed to recover viable V. dahliae microsclerotia using soil plate dilution techniques.