Location: Water Management Research
Project Number: 2034-13000-013-010-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Nov 1, 2022
End Date: Mar 31, 2025
Diversification of a cropping system offers both economic benefits and ecosystem services. During early years, almond trees are non-bearing, but have interrow space that allows forage cultivation and harvest. Project goals are to provide scientific documentation of co-benefits or risks of alfalfa-almond intercropping with regards to orchard soil fertility, water dynamics, profitability, and tree health.
We will establish new almond orchard with research plots to include (i) intercropped alfalfa with flood irrigation, (ii) intercropped alfalfa + flood irrigation + last harvest residues left as green manure, (iii) almond with bare alleys + flood (iv) control, almond with bare alleys no flood (n=5 per treatment). Over two years, approximately eight alfalfa harvests will be collected for yield and forage quality analysis. Soil samples will be collected across the growing season in all treatment plots from alleys and tree rows, from two depths (0-20 and 20-40 cm). Notably, we will quantify soil carbon and nitrogen, compaction, aggregate stability, infiltration, bulk density, and microbial biomass. Fungal pathogens and plant beneficial fungi, such as arbuscular mycorrhizal fungi, will be profiled by sequencing molecular biomarkers (ITS), approximating functional guilds, and via three Phytophthora-specific qPCR assays. Tree growth, nutrition, and root morphology will be monitored to ascertain if alfalfa and/or flooded alleys enhance tree health and robust root systems. Specifically, we will estimate canopy size, vegetation indices, and canopy temperature for almond and alfalfa using light interception and drone-based methods and approximate root morphology using ground penetrating radar technology. Tree nitrogen will also be quantified using leaf tissue analyses.