Soil moisture extraction patterns of different soil-crop combinations as determined by neutron meter

Moisture extraction pattern may be defined as the distribution of water disappearance from the soil profile. It represents water loss through utilization and transpiration by plants and evaporation from the soil. Moisture extraction patterns within the root zone of various crops through progressive stages of growth are important in understanding soil-crop adaptations. It is desirable to know the quantity of soil moisture required for different soil-crop situations and thus arrive at moisture requirements for maximum crop production.

Many methods for determining soil moisture and the moisture extraction patterns of plants have been used. The most common method is that of oven drying soil samples. Other methods which measure soil characteristics such as electrical and thermal conductivity, thermal diffisivity, dielectric constant, and moisture tension are not so direct and none of these methods have been completely satisfactory. In the oven drying method, moisture readings in situ cannot be made. In the indirect methods, calibrations are required and there are many factors in the soil such as temperature, texture, electrical contact resistance, salt concentration, and time of reading, which may disturb or interfere with the results obtained. An approach to a soil-moisture measuring technique that seems to overcome some of the aforementioned difficulties is the neutron method.

This investigation was designed to determine the moisture extraction pattern of several crops growing on different soil types in Tennessee by the use of a neutron moisture meter.