Key points are not available for this paper at this time.
J. L. Harper, J. T. Williams, G. R. Sagar, The Behaviour of Seeds in Soil: I. The Heterogeneity of Soil surfaces and its Role in Determining the Establishment of Plants from Seed, Journal of Ecology, Vol. 53, No. 2 (Jul., 1965), pp. 273-286
Harper et al. (Thu,) studied this question.