Development of sustainable lucerne pastures for wool production. J M van Heerden, ARC-API, PO Box 3320, Matieland.

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1 Development of sustainable lucerne pastures for wool production J M van Heerden, ARC-API, PO Box 3320, Matieland. April 2014 There has been a decrease in the productivity and sustainability of lucerne pastures used in the grain cropping regions of the Western Cape. One of the problems is aphid infestation. This resulted in a decline in the yield of SA Standard, previously the only locally available cultivar. New more aphid resistant cultivars are therefore imported. Many of these cultivars are not persistent under the close grazing employed. Using the correct lucerne cultivar for grazing is therefore of utmost importance. As cultivars change, the process of evaluation of new cultivars for persistence and yield under grazing is a continuous research area. The seed of the new imported lucerne cultivars is, however, very expensive and research also has to be conducted to reduce seeding rates, improve establishment and to increase the lifespan of lucerne pastures. The research focuses on the following aspects: The ongoing evaluation of new lucerne cultivars for grazing The more effective establishment of lucerne The evaluation of new lucerne cultivars for grazing A Trial is being conducted to evaluate 17 lucerne cultivars for yield and persistence under dryland and local grazing conditions in the Caledon district of the Overberg on the Roodebloem Experiment Farm of Overberg Agri. The trial has now completed a three year period (2009 to 2012). The trial was planted in a larger paddock and is utilized and grazed by Merino sheep as part of the farm s grazing system. The cultivars varied in winter activity. The winter activity class of the cultivars is shown in Table 1. Roodebloem receives 67% of its average 550 mm annum -1 of rainfall during the period May to October. The average maximum/minimum temperature during this period is 19.4 o C/7.7 o C, while the drier November to April period has an average maximum/minimum temperature of 26.5 o C/14.3 o C. The experimental sites were previously planted to barley and wheat for five seasons and cultivated twice just before sowing, using a standard shallow tine implement. The soil is of shale origin, stony and of the Klapmuts form and were analysed and fertilised and limed to lift the P (> 30 mg kg -1 P, citric acid method), K (> 50 mg kg -1 K) and ph KCl (> 5.5) levels. 1

2 Individual plot sizes are 16m x 9m. Seed was sown shallowly at 15 kg ha -1 in 150 mm wide rows during May of 2009 using a small plot planter. All seeds were inoculated with the standard commercial lucerne inoculant strain using the standard ph neutral commercial glue, developed for this purpose, before sowing. The lucerne stand density of each cultivar was determined twice, once during each of 2012 and In the past it was estimated as the number of squares containing parts of lucerne within 60 grid 0.25 m 2 quadrates was used as index of cover. But due to the grazing management practices applied to the present trial, lucerne plants were physically dug up the last two years in one 0.40 m 2 sample per plot, counted and weighed (top and root mass). Lucerne yield is determined by cutting 0.17 m 2 samples with sheep shears to ground level every 6 to 8 weeks in and outside each of two round 0.72 m 2 randomly placed welded galvanised wire mesh exclosure cages per plot. The cages are moved to a new random position in a plot after each sampling. The cut samples are washed, dried to constant mass at 59 o C and weighed to determine the dry matter (DM) yield. Yield was calculated as the difference between the available DM outside each cage during the previous sampling date and the available DM within the cage on a particular sampling date. Yield is expressed as kg DM ha -1 annum -1 over the whole period of the trial. Table 1. Cultivars and their winter activity evaluated at Roodebloem, Caledon Cultivar Winter Activity KKS WL903 9 SuperStar 9 SuperCuf 9 KKS Pegasis 8.5 SuperSiriver 8 Magna804 8 WL414 7 SuperAurora 7 SA Select 7 KKS SA Standard 6 Magna601 6 Icon 6 WL357 5 Venus 5 2

3 The data were statistically analysed, using the SAS (2008) program to perform analysis of variance. Results Annual dry matter yield The average seasonal dry matter yield of the 17 cultivars over the whole trial period is shown in Tables 2 to 5. There was a significant (P<0.05) interaction in the yield and season for the cultivars. During May to June (Table 2) SA Select, during the August to October (Table 3) WL 414, during November to January (Table 4) Super Aurora and during February to April (Table 5) Magna 804 tended to be highest yielding. SA standard was one of the lowest yielding cultivars during all seasons. Table 2. The May to July yield of 17 lucerne cultivars over five years at Roodebloem, Caledon. Data followed by the same letters do not differ significantly (P<0.05) Cultivar Seasonal Yield kg ha -1 Season -1 SASelect 563 bcde Magna cdefg KKS cdefg SuperSiriver 492 cdefgh Pegasis 491 cdefgh SAStandard 485 cdefgh WL cdefgh Icon 455 efghi SuperStar 444 efghi KKS efghi SuperAurora 420 efghi Venus 358 hijklmn SuperCuf 337 ijklmn WL ijklmn Magna mnopq WL mnopqrst KKS pqrstuvwx 3

4 Table 3. The August to October yield of 17 lucerne cultivars over five years at Roodebloem, Caledon. Data followed by the same letters do not differ significantly (P<0.05) Cultivar Seasonal Yield kg ha -1 Season -1 WL a Magna ab Magna abc SuperSiriver 601 abcd KKS bcde Venus 554 bcdef WL cdefg Pegasis 518 cdefg WL cdefg SASelect 465 defghi Icon 464 defghi SuperAurora 451 defghi SuperStar 423 defghi KKS ghijkl KKS hijklm SuperCuf 327 jklmno SAStandard 240 mnopqrst Table 4. The November to January yield of 17 lucerne cultivars over five years at Roodebloem, Caledon. Data followed bay same letters do not differ significantly (P<0.05) Cultivar Seasonal Yield kg ha -1 Season -1 SuperAurora 193 opqrstuvw KKS qrstuvwxy KKS qrstuvwxyz Magna qrstuvwxyz WL qrstuvwxyz Magna rstuvwxyz WL stuvwxyz WL tuvwxyz Venus 92 uvwxyz SAStandard 90 vwxyz SASelect 72 wxyz Icon 63 wxyz SuperCuf 47 xyz Pegasis 45 xyz SuperSiriver 34 yz KKS yz SuperStar 16 z 4

5 Table 5. The February to April yield of 17 lucerne cultivars over five years at Roodebloem, Caledon. Data followed bay same letters do not differ significantly (P<0.05) Cultivar Seasonal Yield kg ha -1 Season -1 Magna klmnop KKS lmnopq Magna mnopqr WL mnopqr Venus 262 mnopqr WL mnopqrs WL mnopqrst SuperAurora 249 mnopqrst Icon 248 mnopqrst SuperStar 242 mnopqrst KKS mnopqrst SASelect 232 mnopqrst Pegasis 229 mnopqrstu SuperSiriver 222 mnopqrstuv SAStandard 217 nopqrstuv KKS qrstuvw SuperCuf 151 qrstuvwxyz Lucerne population The average number of lucerne plants differed significantly (P<0.05) between cultivars. The results are shown in Tables 6 to 8. Pegasis tended to have the most plants and Super Cuf the lowest (Table 6). The number of lucerne plants declined significantly (P<0.05) from 2012 to 2013, but the cultivars did not respond significantly (P<0.05) differently (Table 7). The mass per individual lucerne plant differed significantly (P<0.05) between cultivars and KKS 7000 tended to have the largest mass per plant and SA Select lowest (Table 8). The mass per plant increased significantly (P<0.05) from 2012 to 2013 (Table 9). Figure 1 clearly shows that there was a negative relationship between plant number and plant mass. Individual plant size thus declined with increased plant numbers. Conclusions Research executed over many years, have shown lucerne to be very responsive to grazing management. The yield, quality and persistence of this pasture legume are severely influenced by the frequency and intensity of utilization, although cultivars differ in their sensitivity to grazing management. Level and frequency of grazing further also influences the competitiveness of lucerne with annual winter broad leaf and grass weeds in the winter rainfall area. The fact that this trial, in contrast to the previous two conducted from 2001 to 2009, was not 5

6 fenced of and grazed continuously and severely may have influenced the results. The more winter active cultivars therefore performed relatively better in contrast to those which are more winter dormant and perhaps more prone to competition from annual winter weeds. Table 6. Number of plants m -2 for each cultivar over two seasons 2012 and 2013 at Roodebloem, Caledon Kultivar Mean Pegasis 66.2 a SA Standaard 65.8 a SA Select 65.0 a Magna ab Venus 49.8 abc Icon 41.7 bcd Super Siriver 40.2 bcde WL bcde Super Aurora 37.5 bcdef WL cdef WL cdef Magna cdef KKS cdef Super Star 30.3 cdef KKS def KKS ef Super Cuf 17.2 f Table 7. Number of plants m -1 per season over cultivars at Roodebloem, Caledon Datum Mean 29/9/ a 24/8/ b The grazing management of the trial could therefore have influenced the relative yield of the cultivars. It is, however, clear and also welcomed that some of the more winter active cultivars performed well in comparison to the more dormant cultivars. The trial should continue for at least another season. Future trials should, however, again be fenced off to allow the proper management of the trial, without undue interference with the running of the farm. 6

7 Table 8. Mass per lucerne plant (g plant -1 ) for each lucerne cultivars over two season 2012 and 2013 at Roodebloem, Caledon Kultivar KKS 7000 Magna 804 Super Cuf Super Star WL 903 KKS 4000 Super Aurora Magna 601 WL 357 KKS 9911 WL 414 Super Siriver Venus Icon Pegasis SA Standaard SA Select Mean 4.66 a 4.21 ab 4.09 ab 4.04 ab 3.63 abc 3.62 abc 3.52 bcd 3.44 bcd 3.41 bcde 3.34 bcde 3.28 bcdef 3.26 bcdef 2.81 cdef 2.78 cdef 2.46 def 2.32 ef 2.22 f Table 9. Mass per lucerne plant (g plant -1 ) over all cultivars in successive years at Roodebloem, Caledon Datum Mean 29/9/ b 24/8/ a 7

8 lucerne Mass plant -1 (g) 5.0 Figure 1. Relationship between the number of lucerne plants and the mass per plant over two years (2012 and 2013) at Roodebloem, Caledon Number of lucerne plants m -2 The establishment of lucerne Trials are conducted in which seed treatments, aimed at increasing the rate of lucerne seedling establishment, are evaluated. A number of trials have been completed the last three years and some of the treatments have had a major positive influence on the number of lucerne seedlings that establish. Higher establishment rates resulted in better stands and also allow for lower seeding rates and thus lower lucerne establishment cost. The interaction of seeding rate and seed treatment is also studied. A trial was planted at Caledon where the treated (T) and untreated (I) seed of two cultivars SA Select and WL414 was sown at seeding rates from 1 to 20 kg ha -1.applied to WL414 resulted in heavier seeds and this resulted in a lower number of seeds being sown. This was not as pronounced in the case with the SA Select (T) treatment. The number of seedlings establishing at the WL414 (T) treatment was also lower than for the untreated, WL414 (I) treatment. In contrast the SA Select (T) treatment improved the number of seedlings establishing in comparison to the untreated SA Select (I). This indicates that seed treatments applied by certain companies are not effective. It is therefore a very important aspect to consider when buying pre-treated lucerne seed. Another aspect to consider is that no treatments have been registered at this stage and it would therefore be illegal to recommend any specific treatment(s). Seeding rate also influenced lucerne yield. From the 2011/12 results it was clear that the maximum dry mass m -2 was reached at a seedling number of 150 seedlings m -2. This trial is continuing and further plant 8

9 - Number of lucerne plant s.m counts were conducted during 2012 and These results are shown in Figure Figure 2. Relationship between number of viable lucerne seeds sown in 2011 and the number of lucerne plants in 2011, 2012 and in each year y = 0.155x R² = y = 0.088x R² = y = 0.047x R² = Number of viable lucerne seed.m - 2 sown in Figure 2 shows that the number of lucerne plants establishing increased with seeding rate. The number of plants declined over season at all seeding rates. 9