This experiment quantified the impacts of cultivar, companion grass, harvest schedule and N fertiliser on herbage ensilability at each of four harvests in the second year after sowing

Black, A.D.

O'Kiely, P.

Organic Eprints

Red clover for silage: management impacts on ensilability indices in the second season after sowing  P. O’Kiely and A.D. Black Teagasc, Grange Beef Research Centre, Dunsany, Co. Meath  Introduction The ensilability of swards containing red clover (Trifolium pratense) is influenced by a range of management factors. This experiment quantified the impacts of cultivar, companion grass, harvest schedule and N fertiliser on herbage ensilability at each of four harvests in the second year after sowing.  Materials and Methods Within a randomised complete block (n=4) design, field plots (16 per block, each 10m x 2m) were used to evaluate a 2 (cultivars) x 2 (alone or with companion grass) x 2 (harvest schedule) x 2 (application of N fertiliser in spring) combination of factors. Two cultivars of red clover (Merviot and Ruttinova) were each  sown in autumn as a monoculture or with perennial ryegrass (Lolium perenne, cv. Greengold). They received 0 or 50 kg inorganic N fertiliser/ha in mid-March and had a first-cut harvest date of 31 May or 13 June. Sequential harvests following 31 May were taken after 46, 48 and 57 days, with the corresponding durations after 13 June being 47, 42 and 49 days. All plots were harvested to a 5 cm stubble height and received P and K after each harvest. Clover data were analysed using a General Linear Model that accounted for each of the four factors and all two-, three- and four-way interactions.   Results and Discussion The mean annual proportion of red clover in the monocultures was 0.79 compared with 0.70 for the binary mixtures (s.e.m. 0.026; P<0.05). The corresponding values for no N or N being spread in March were 0.79 and 0.70 (s.e.m. 0.026; P<0.05) and for the early and late harvest regimes were 0.80 and 0.69 (s.e.m. 0.026; P<0.01). Whereas red clover cultivar had little effect on ensilability indices (Table 1), inclusion of ryegrass with red clover reduced sward buffering capacity (BC) at Harvests 1 (P<0.001), 2 (P<0.01) and 4 (P<0.05), and increased (P<0.05) water-soluble carbohydrates (WSC) at Harvest 4. Spring application of N increased (P<0.05) WSC at Harvests 1 and 3, and reduced BC at Harvest 1 (P<0.001) but increased (P<0.05) it at Harvest 3. It increased (P<0.01) dry matter (DM) content  at Harvest 1 but reduced (P<0.05) it at Harvest 3. The late harvest schedule increased (P<0.001) DM content at Harvests 1 and 3, reduced WSC at Harvests 1 (P<0.001), 2 (P<0.05) and 3 (P<0.001), and reduced (P<0.001) BC at Harvests 2 and 3. A small number of 2- and 3-way interactions occurred.  Conclusions Both red clover cultivars had similar ensilabilities. Binary mixtures of red clover and ryegrass should be easier to preserve as silage than red clover monocultures due to higher WSC and/or lower BC. Spring applied N generally improved ensilability by increasing WSC and/or reducing BC. Much of the effects of binary mixtures versus monocultures, or of spring applied N, were due to increasing the proportion of ryegrass in the sward. The impact of the late harvest regime was more difficult to assess as it generally increased DM but reduced WSC and BC.     Table 1. Herbage ensilability indices for each harvest in the second season after sowing Red clover Grass1 N2 Harv. Harvest 1 Harvest 2 Harvest 3 Harvest 4      cultivar   sched.3 DM4 WSC5 BC6 DM WSC BC DM WSC BC DM WSC BC Merviot No No Early 148 73 433 130 85 499 126 76 538 159 50 511   No No Late 153 33 411 138 82 447 148 27 348 167 46 527  No Yes Early 148 75 411 134 83 499 127 72 537 141 47 555   No Yes Late 172 44 412 137 70 464 137 34 445 148 49 557  Yes No Early 145 67 393 136 96 495 128 67 560 139 44 546  Yes No Late 154 32 388 134 54 414 144 27 348 147 52 505  Yes Yes Early 146 100 383 131 77 486 134 81 546 141 41 540   Yes Yes Late 160 49 325 133 84 453 126 40 454 157 74 471 Ruttinova No No Early 139 65 442 129 75 514 125 66 565 152 42 562  No No Late 152 67 425 130 65 478 144 30 388 149 42 595  No Yes Early 144 82 406 129 75 517 116 72 561 146 46 539  No Yes Late 164 34 417 132 66 455 135 38 444 152 40 537  Yes No Early 137 77 415 130 78 503 125 69 549 151 49 538  Yes No Late 138 33 408 133 65 459 144 32 396 162 51 503  Yes Yes Early 146 97 375 133 65 493 119 70 546 155 64 535   Yes Yes Late 151 34 355 133 60 419 144 30 395 151 79 512  s.e.m.7    5.4 8.1 16.0 4.0 8.7 11.8 4.5 4.4 27.0 8.2 9.3 21.8 1With companion perennial ryegrass; 2Application of inorganic N in spring; 3Early or late first-cut harvest schedule; 4Dry matter (g/kg); 5 Water-soluble carbohydrates (g/kgDM); 6 Buffering capacity (mEq/kgDM); 7For 4-way interaction.  

Red clover for silage: management impacts on ensilability indices in the second season after sowing

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