1. Cyclic variations and the pedon;Arnold,1964
2. Soil variability: a review;Beckett;Soils Fert.,1971
3. Precision tillage effects on potato root and tuber production;Bishop;Am. Potato J.,1978
4. Bulk density;Blake,1965
5. A case study on the effect of soil compaction on potato growth in a loamy sand soil. 1. Physical measurements and rooting patterns;Boone;Neth. J. Agric. Sci.,1978