1. Arya LM, Farrel DA and Blake GR (1975) A field study of soil water depletion patterns in presence of growing soybean roots. I. Determination of hydraulic properties of the soil. Soil Sci Soc Am Proc 39: 424?430
2. De Vos JA, Inckel MS and Raats PAC (1990) The water balance of the unsaturated zone, considered within the context of sustainable agriculture. In: Van Genuchten R (ed) Proc Workshop ?Indirect methods for estimating the hydrolic properties of unsaturated soils?, October 11?13 1989, Riverside, California (in press)
3. Drew MC and Saker LR (1980) Assessment of a rapid method using soil cores, for estimating the amount and distribution of roots in the field. Plant and Soil 55: 297?305
4. Groot JJR (1987) Simulation of nitrogen balance in a system of winter wheat and soil. Simulation Report CABO-TT no. 13, Centre for Agrobiological Research, and Department of Theoretical Production Ecology, Agricultural University, Wageningen, 69 p
5. Soil Science Society of America (1987) Glossary of soil science terms. Soil Science Society of America, Madison, Wisconsin, 44 p