Browsing by Author "Van Huyssteen, L."

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    The effect of conventional and minimum tillage practices on some soil properties in a dryland vineyard
    (South African Society for Enology and Viticulture, 1980) Van Huyssteen, L.; Weber, H. W.
    Preliminary results of a long-term viticultural tillage experiment comprising two groups of treatments, are reported. These groups are (i) a group of "minimum" tillage practices having received no mechanical soil tillage at all, and (ii) a group of "conventional" tillage treatments according to long-established local practices by disc-harrow. The "minimum" group consists of: (a) a permanent straw mulch cover, (b) chemical weed control, and ( c) a permanent cover of indigenous weeds frequently cut by a bush-cutter. The "conventional" group consists of: (a) deep and (b) shallow trench furrow systems, and (c) the locally customary "clean cultivation" system. A comprehensive investigation into the changes of sleeted soil properties after a period of eight years revealed significant differences between properties of the soil under minimum tillage (group (i)) and under clean cultivation (group (ii)). Soil parameters, such as pore volume distribution, compaction indices, activity of micro-organisms and availability of plant nutrients, were found to be more favourable in some minimum tillage treatments than on the conventionally tilled plots.
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    The effect of selected minimum and conventional tillage practices in vineyard cultivation on vine performance
    (South African Society for Enology and Viticulture, 1980) Van Huyssteen, L.; Weber, H. W.
    A long-term vineyard cultivation experiment, comprising six tillage treatments which represent a "conventional'' cultivation group as well as a group of "minimum" tillage practices, was started in 1968 at Nietvoorbij Experimental Farm of the OVRI, Stellenbosch. The first group included (i) the "shallow trench furrow", (ii) the "deep trench furrow", and (iii) the locally customary "clean cultivation" systems, and the second group comprised (i) a straw mulch cover on the soil surface, (ii) chemical weed elimination by herbicides, and (iii) a permanent "sward" of indigenous weeds. Distinct differences in vine performance between treatments were found. The general appearance, nutritional status and some important growth parameters of vines, as well as yield and quality of grapes, musts and wines from the straw mulch and herbicide treated (minimum) plots were markedly superior to the same properties of vines, grapes and wines from the conventionally tilled plots and the sward treatment, the latter due to competition of weeds for water and nutrients. However, a tentative economical analysis showed that the deep furrow trenching gave a sufficiently high yield to merit further consideration, although it could not reach the economical performance of the herbicide treatment.
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    Soil moisture conservation in dryland viticulture as affected by conventional and minimum tillage practices
    (South African Society for Enology and Viticulture, 1980) Van Huyssteen, L.; Weber, H. W.
    The effect of conventional clean cultivation, a straw mulch, chemical weed control and a grass sward on the soil moisture regime in a dryland vineyard was investigated. The results demonstrate that both a straw mulch and chemical weed control were very effective ju conserving winter-stored soil moisture until mid- or even late summer to support the vines during the almost rainless growing season. Further, it appeared that a mere loosening of the soil surface periodically by way of clean cultivation cannot conserve soil moisture effectively; it may, on the contrary, promote evaporation in the top-soil layers, especialzy when done after rain. On the other hand, an undisturbed soil surface, as in the case of chemical weed control, acts as a mulch in itself after the surface layer has dried out, thus reducing evaporation. Even under conditions of frequent rainfall, as during the first part of 1976/77 season, the straw mulch cover treatment was still superior to all other treatments in conserving soil moisture.