Sucrose yield of sugar beet as affected by chiseling and plowing compacted soils

Abstract

Sugar beet ( Beta vulgaris L.) growers in Nebraska, U.S.A. have been convinced by equipment manufacturers in the past 10 years that chisel tillage is needed on their soils to remove compaction zones. No data were available to assess the reality of their conviction that chiseling was an essential part of their tillage systems. The experiments discussed here were designed to test the impact and need for chiseling to depths up to 30 cm in systems where moldboard plowing to a depth of 20 cm is the most common primary tillage. Various degrees of soil compactness were created artificially in soil of the same type (Typic Haplustoll) in 3 different fields. Combinations of moldboard plowing and chiseling were then imposed on them. The relationships of water infiltration rates and resistance to penetration as measured by a penetrometer to the tillage treatments and to ultimate sucrose yield were determined. In all but the severest compaction treatment, either chiseling or moldboard plowing had equivalent impacts on yield restoration. In the most severely compacted soil chiseling was totally ineffective in 1 year and equal to plowing in another year. Combination plowing and chiselinng did not have an additive effect beyond plowing or chiseling along under any compaction condition. Even though the implements were equally effective in restoring yield potential, neither of them, alone nor in combination restored yields to levels achieved on non-compacted soil. Penetrometer resistance measurements indicated that compacted soil below 30 cm was the problem. The data indicated that it may be possible for a given soil type, to relate penetrometer resistance to the need for tillage to remove compaction. On these experiments each increase in resistance of 700 kPa over a range of 4000–8000 kPa resulted in a 10% reduction in sucrose yield.