Effect of planting dates and cutting stages on raphanus sativus and brassica rapa in contribution of fodder flow planning

Abstract

In the summer rainfall areas of South Africa small scale farmers, as well as commercial farmers experience low animal production due to a lack of good quality roughage. The nutritional value of the rangeland cannot maintain livestock during autumn and winter. Producing winter fodder could be expensive and literature showed that planting fodder radish and turnip might be a cheap relative option (not in sweet veld). Winter supplementation contributes largely to high input costs in livestock production, which can make this enterprise uneconomically. For this reason alternative winter feeding strategies should be investigated, like the use of Brassica and Raphanus species for feed supply, of high quality, in winter. Two Localities [Syferkuil, (University of Limpopo’s experimental farm (Limpopo) and Dewageningsdrift, (Hygrotech Experimental farm (Gauteng)] were used for this research project. On the two localities three different factors were tested:  Three planting dates (February, March and April)  Three cultivars (Nooitgedacht fodder radish, Forage star turnip (not on Syferkuil) and Mammoth purple top turnip)  Three cutting frequencies (first cut10 weeks after planting + regrowth; first cut 14 weeks after planting + regrowth and 18 weeks after planting, no regrowth). Samples (for dry matter production and nutritional value analysis) were collected at both localities as per cutting frequency treatments during the 2007 growing season. The samples were used to evaluate the influence of the mentioned treatments on total dry matter production, nutritional value, leaf production and tuber production of the three cultivars. At Syferkuil the DM production Nooitgedacht fodder radish was higher (5.23 to 5.9 t/ha) than that of Mammoth purple top turnip (3.24 t/ha) when planted in February. The same trend was seen during the March planting date (4.7 t/ha and 3.6 t/ha respectively for 18 W treatment). During the April planting date the highest production was higher (5.07 t/ha and 5.13 t/ha respectively) than that of the March iv planting date. The 10 Weeks + Re-growth cutting treatment resulted in general in the lowest production. At Dewageningsdrift (Gauteng) Nooitgedacht fodder radish produced the highest of all three cultivars at the 18 Weeks treatment, with the highest when planted in March (7.67 t/ha), 5.5 t/ha when planted in April and 5.3 t/ha when planted in February. For the rest of the treatments the DM production of Nooitgedacht varied between 2.9 t/ha and 4.6 t/ha. The highest DM production of Forage star turnip was 3.01 t/ha (10 W+R, February planting date), 1.35 t/ha (14 Weeks + Re-growth, March planting date) and 2.34 t/ha (18 Weeks, April planting date). The highest DM production of Forage star turnip was 2.96 t/ha (18 Weeks, February planting date), 2.59 t/ha (14 Weeks + Re-growth, March planting date) and 4.1 t/ha (18 Weeks, April planting date). An estimation of the grazing/feeding potential of the different cultivars, at different planting dates and defoliation/cutting treatments, was calculated by using the leave and tuber production (variable criteria) from each treatment. The period from the initial cut to the last regrowth cut was a second variable criterion that was used. The third criterion (non-variable) was the standard norm that the daily intake of a matured livestock unit (MLU) of 450 kg is 10 kg. According to the results the following example of a combination of treatments can be used to maintain ± 10 MLU/ha for the longest period in the winter in Limpopo: Plant 1.1 ha Nooigedacht radish in February, utilize from ± 27 April to 22 June, Plant 2.4 ha Nooigedacht radish in April, utilize from ± 22 June to 27 August, Plant 0.9 ha Mammoth purple top in April, utilize from ± 20 August to 3 Oct According to the results the following example of a combination of treatments can be used to maintain ± 10 MLU/ha for the longest period in the winter in Gauteng: Plant 2.1 ha Forage star turnip in February, utilize from ± 12 April to 13 June, Plant 1.7 ha Mammoth purple top in February, utilize from ± 7 June to 28 July, Plant 1.5 ha Forage star turnip in April, utilize from ± 18 July to 29 August, Plant 2.1 ha Forage star turnip in April, utilize from ± 17 August to 4 Oct.