Tilth index: an approach to quantifying soil tilth.
1992
Singh K.K. | Colvin T.S. | Erbach D.C. | Mughal A.Q.
Tilth is a qualitative term that describes the physical state of soil. There is need for a quantitative understanding of soil tilth to help scientists, engineers, and farmers better understand how to manage soil. A "tilth index" based upon five soil physical properties was developed to quantify tilth. Values of bulk density, cone index, aggregate uniformity coefficient, organic matter content, and plasticity index were used to calculate an index, that ranges from zero for conditions unusable by the plant to one for a soil that is nonlimiting for plant growth. The tilth index was evaluated in field experiments near Ames, Iowa, and Waseca, Minnesota. The tilth index significantly changed during the cropping season. The tilth index was increased by tillage and planting operations and then decreased with time until harvest. The tilth index was positively correlated (r2 ranging from 0.15 to 0.86, with 10 of 16 values more than 0.60) with yields of corn and soybean. When compared with a modified productivity index the tilth index was more responsive to tillage and provided better correlations with crop yield.
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