Soil and Crop Response to Varying Levels of Compaction, Nitrogen Fertilization, and Clay Content.
Gregorich, E.G., Lapen, D.R., Ma, B.-L., McLaughlin, N.B., and VandenBygaart, A.J. (2011). "Soil and Crop Response to Varying Levels of Compaction, Nitrogen Fertilization, and Clay Content.", Soil Science Society of America Journal, 75(4), pp. 1483-1492. doi : 10.2136/sssaj2010.0395
Compaction affects nearly all soil properties and functions, thereby affecting the growth, distribution, and function of roots, and crop productivity. Our objectives in this research were to evaluate the effects of compaction, N fertilization, and soil texture on corn (Zea mays L.) growth and yield and to determine whether additional N fertilization could compensate for lower yields caused by compaction. Soil was differentially compacted for 3 yr to create two compaction treatments in Year 1 and four in Years 2 and 3; N fertilizer was applied at two rates in Year 1 and four different rates to each compaction treatment in Years 2 and 3; yield was measured in each of the 3 yr, and soil and crop growth properties were measured after 2 and 3 yr. Variation in soil texture across the experimental plots allowed us to partly assess the effects of clay content on the soil and crop response to compaction. Compaction substantially reduced plant growth and productivity; yields were reduced by up to 2.7 Mg ha-1 (33%) and dry matter by 4.1 Mg ha-1 (26%) in compacted soils. Avoiding compaction for a year appeared to allow crop growth and yields to recover. For example, grain yield after two consecutive years of compaction (5.21 Mg ha-1) was significantly lower than after 1 yr of compaction followed by no compaction (7.59 Mg ha-1). Compaction increased soil strength near the bottom of the plow layer, where a carryover effect of compaction was apparent. Compaction-induced yield reductions were greatest on soils with more clay and were attributed to adverse soil physical conditions rather than limited N fertility.