Control of Soil Moisture and Rhizosphere Activity of Corn (Zea mays) on Soil Nutrient Availability and Plant Nutrient Uptake in Two Different Soil Types of North Dakota.

Nutrient availability in soil depends upon several factors and complex interactions among them. Soil moisture is one of the most important factor in governing plant nutrition by its influence on nutrient movement, solution chemistry and microbial activity. Available nutrient concentration in soil is generally determined using soil test which is often very poorly correlated because of the rhizosphere effect and various dynamic properties of soil, especially soil moisture content. A greenhouse experiment has been conducted to investigate how the moisture and rhizosphere environment controls the macro and micro nutrient availability in soil over a specific period of time using the PRS^® probe and corn as test plant in 2016 at North Dakota State University. The experiment has been conducted in factorial completely randomized design with 12 treatment combinations [2 soil types (Downer and Inkster) × 3 moisture levels (40%, 60% and 80% of field capacity) × 2 rhizosphere environment (with and without plant)] and 4 replications. Two pairs of fresh anion and cation exchange resin probes (PRS^®) were inserted in each pot at a depth of 3″ (centered) for three days at V3 and V7 stages to estimate the macro and micronutrient availability and potential nutrient release. Above-and belowground plant biomass will be recorded after V7 stage days and plant samples will be analyzed to determine the nutrient uptake. Homogenized soil samples of each pot will be analyzed for exchangeable nutrient concentrations. A mechanistic model using Michaelis-Menten equation will be developed to determine nutrient availability and uptake for three moisture levels for two soils. Outcomes from this experiment will determine the feasibility of predicting the plant nutrient uptake based on soil moisture and nutrient availability. Moreover, this project will determine whether PRS^® probe has potential to replace traditional soil and tissue testing program.