TY - JOUR

T1 - Reduced tillage and compost effects on soil aggregate stability of a silt-loam Luvisol using different aggregate stability tests

AU - Obalum, S. E.

AU - Uteau-Puschmann, D.

AU - Peth, S.

N1 - Funding information: This study is part of OSCAR (Optimising Subsidiary Crop Application in Rotations) Project on developing a sustainable conservation agriculture system using flexible reduced tillage and subsidiary crops, funded by the EU 7th Framework Programme (Grant Number 289277 ). The study was executed during March–May 2015 while author SEO was on a TWAS-DFG Cooperation Visit for postdoctoral researchers from aharan Africa at the Department of Soil Science, Faculty of Ecological Agriculture, University of Kassel, Witzenhausen, Germany (Grant Number PE 1523/6-1 ). The support of TWAS-DFG for the short-term fellowship is gratefully acknowledged. Thanks to Mr Markus Hammer-Weiss and Ms Margit Rode for field and laboratory assistance.

PY - 2019/6

Y1 - 2019/6

N2 - Aggregate stability of soils informs about their relative strengths against erosive forces and mechanical disruption; however, the many methods of assessment are not of equal potential in discriminating management effects. Moreover, the index to mimic the actual behaviour of field soils is not readily discernable from such assessment. In this study involving a silt-loam Luvisol on long-term tillage trial in Central Germany, we assessed topsoil aggregate stability 2.5 years after initiating the experiment using selected laboratory methods from which 12 indices were derived. Our aim was to assess treatment effects on aggregate stability as discriminated by the indices, explore the relationships among them, and relate them to simulated erosion of the soil. Treatments were reduced tillage and conventional tillage each with compost at 0 and 5 t ha –1 . The indices included mean-weight diameter after dry (MWD d ) and wet (MWD w ) sieving, sand-corrected water-stable aggregates (%WSA cfs ), aggregate stability index (ASI), percolation stability (PS), sealing index (SI); and tensile strength of 24-16, 16-8 and 8-4 mm air-dry (TS ad ) and re-moistened (TS rm ) aggregates. The SI method used rainfall simulation which enabled measurements of runoff and mass of eroded sediment (MASED eroded ). Tillage-×-compost interactions on aggregate stability were consistently non-significant. Four of the indices discriminated between the tillage systems; three (MWD w , WSA cfs and TS rm(16-8) ) showed higher stability under reduced tillage while ASI showed otherwise. Two (ASI and SI) favoured compost non-application. MASED eroded correlated with PS, %WSA cfs and MWD d (r = –0.53 * , –0.51 * and 0.49 * , respectively), with best fit as logarithmic, exponential and polynomial, respectively. Also, MASED eroded was explained by PS and two of the aggregate size fractions from dry sieving (p ≤ 0.002; R 2 = 0.700). To enhance aggregate stability and reduce water erosion in this soil, reduced tillage is a good candidate while compost may be unnecessary in the short run. The indices PS, %WSA cfs and MWD d can mimic water erodibility of the soil. The inclusion of MWD d usually associated with wind erosion among these indices found relevant for water erosion is remarkable.

AB - Aggregate stability of soils informs about their relative strengths against erosive forces and mechanical disruption; however, the many methods of assessment are not of equal potential in discriminating management effects. Moreover, the index to mimic the actual behaviour of field soils is not readily discernable from such assessment. In this study involving a silt-loam Luvisol on long-term tillage trial in Central Germany, we assessed topsoil aggregate stability 2.5 years after initiating the experiment using selected laboratory methods from which 12 indices were derived. Our aim was to assess treatment effects on aggregate stability as discriminated by the indices, explore the relationships among them, and relate them to simulated erosion of the soil. Treatments were reduced tillage and conventional tillage each with compost at 0 and 5 t ha –1 . The indices included mean-weight diameter after dry (MWD d ) and wet (MWD w ) sieving, sand-corrected water-stable aggregates (%WSA cfs ), aggregate stability index (ASI), percolation stability (PS), sealing index (SI); and tensile strength of 24-16, 16-8 and 8-4 mm air-dry (TS ad ) and re-moistened (TS rm ) aggregates. The SI method used rainfall simulation which enabled measurements of runoff and mass of eroded sediment (MASED eroded ). Tillage-×-compost interactions on aggregate stability were consistently non-significant. Four of the indices discriminated between the tillage systems; three (MWD w , WSA cfs and TS rm(16-8) ) showed higher stability under reduced tillage while ASI showed otherwise. Two (ASI and SI) favoured compost non-application. MASED eroded correlated with PS, %WSA cfs and MWD d (r = –0.53 * , –0.51 * and 0.49 * , respectively), with best fit as logarithmic, exponential and polynomial, respectively. Also, MASED eroded was explained by PS and two of the aggregate size fractions from dry sieving (p ≤ 0.002; R 2 = 0.700). To enhance aggregate stability and reduce water erosion in this soil, reduced tillage is a good candidate while compost may be unnecessary in the short run. The indices PS, %WSA cfs and MWD d can mimic water erodibility of the soil. The inclusion of MWD d usually associated with wind erosion among these indices found relevant for water erosion is remarkable.

KW - Compost application

KW - Percolation stability

KW - Sealing index

KW - Sieving technique

KW - Tensile strength

KW - Tillage systems

UR - http://www.scopus.com/inward/record.url?scp=85061631943&partnerID=8YFLogxK

U2 - 10.1016/j.still.2019.02.002

DO - 10.1016/j.still.2019.02.002

M3 - Article

AN - SCOPUS:85061631943

VL - 189

SP - 217

EP - 228

JO - Soil and Tillage Research

JF - Soil and Tillage Research

SN - 0167-1987

ER -