Plant growth as a function of soil texture in the Hanford series

At the Kearney Horticultural Field Station, in soils of the Hanford series, cantaloupe plant growth and yield varied from excellent to poor as the sand content of the soil varied from about 40 per cent to 70 per cent. Experiments described here indicated that tendencies to moisture stress or nutritional deficiency were not the primary factors limiting plant growth on the coarser soil. Observations upon roots indicated a greater mechanical impedance to root growth in the coarser soil, although this was not reflected in penetrometer measurements, and although the rate of water percolation was higher for the coarser than for the finer soil. Since, in response to textural variation, plant development in pot culture was analogous to that in the field, the field profile did not appear to be a principal factor in the response phenomenon. A two-point hypothesis which fits all the observations is offered to explain the relationship between soil texture and plant growth: (1) for cantaloupe, pore sizes in both the coarser and finer members of this soil were too small for root extension; (2) adequate root extension occurred in the finer soil via fractures which developed during moisture loss. Fractures do not develop in the coarser soil. The response of cotton and of some woody species to textural variations in this soil is similar to that of cantaloupe.