1. logo here… Impact of long-term wheat production management practices on soil acidity, phosphorus and some micronutrients in a semi-arid Plinthosol P.F. Loke, E. Kotzé & C.C. Du Preez Department of Soil, Crop and Climate Sciences University of the Free State, Bloemfontein, South Africa. 10 th Inkaba yeAfrica/!Khure Africa (AEON) Conference/Workshop Lord Milner Hotel, Matjiesfontein - Karoo 29 September – 3 October 2014

2. Introduction Soil vs Bank Acc. Objectives: - Evaluate long-term effects of wheat production management practices on soil acidity and some essential nutrients. -Establish whether differences in wheat grain yield occurred as a result of the applied treatments. NB: You withdraw only what you put in.

3. Material and methods  Treatments:  Sampling and analysis: six soil layers and analyzed for pH, P, Cu, Fe, Mn and Zn Stubble Mulch (SM) Ploughing (MP) No-tillage (NT) -Straw was burned (B) or left unburned (UnB) -Weeds were controlled chemically (Chem) or Mechanically (Mech) Plinthosol Layers (mm) 0-50 50-100 100-150 150-250 250-350 350-450

4. Results Soil prop. Depth (mm) Straw TillWeed Optimum values UnBBNTSMMPChemMech pH0-1506.56.46.76.46.36.46.55.5-7.5 0-2506.26.3 6.2 6.3 P0-15023262923212721>12 0-25021232521 2419 Cu0-1501.41.3 1.4 >0.3 0-2501.51.4 1.51.4 1.5 Fe0-15052505651455052>2.0 0-25056595869465956 Mn0-1502628272925 29>2.5 0-2502426242624 26 Zn0-1501.61.81.91.81.41.61.8>0.3 0-2501.51.6 1.71.31.51.6 Weighted means of soil pH(H 2 O) and some nutrients (mg kg -1 ) to 150 mm and 250 mm soil depths inside the trial cropped annually with wheat

5. Period Straw Till Weed UnBBHSD T NTSMMPHSD T ChemMechHSD T 1979-102.282.120.04 2.112.192.280.07 2.202.19ns 1979-902.191.990.07 2.042.072.160.11 2.072.17ns 1991-001.941.90ns 1.851.902.020.15 1.941.90ns 2001-102.472.250.08 2.332.292.460.11 2.382.35ns Effect of straw management, tillage and weeding methods on wheat grain yield (t ha -1 ) over 32 years HSD T significant at P < 0.05 ns = non-significant Conclusion  It is evident that proper crop residue management can improve soil fertility.  However, more work needs to be done to identify and rectify yield associated problems that resulted in lower yields in No-tilled and stubble mulched plots.

6. Currently The influence of land use on organic matter content and related components on Vertisols: Land use: -Grassland-to-cropland conversion chronosequence -Cropland-to-grassland reversion chronosequence -Grassland (reference) Parameters: 1. Organic matter content: SOC and TN stocks (Mg/ha) 2. Related components: Labile organic matter fractions, Microbial residues (Amino sugars and Glomalin), lignin, humic substances, soil enzymes and Isotopic signatures of SOM ( 13 C and 15 N)

7. Thank You Grassland to Cropland Cropland to Grassland