THERE is renewed interest in utilising white clover in grazing swards. Mixed swards of clover and perennial ryegrass have a number of potential benefits.
As clover is a legume, it has the ability to fix atmospheric nitrogen and make it available to the sward, thus reducing fertiliser inputs. Clover also helps to maintain herb-age quality and sward palatability over the summer months compared to grass only swards. It is also more drought resistant and will maintain forage production in a dry summer. The benefits of clover in a grazing sward are realised from May onward as soil temperatures increase.
Kathryn George, CAFRE Da-
irying Adviser, says: “It is important to understand the growth phases of clover and subsequent management practices to ensure a return on investing in clover. It will be 12-18 months before any significant ni-
trogen fixing be-
nefits of clover begin.
“This is due to the clover plant going through a nu-
mber of ph–ases during establishment.
“After germination, the clover plant seedling is entirely reliant on a tap root for approximately three months. Then the plant moves into the expansion phase whereby it is still reliant on the tap root, however the stolons (horizontal roots at the soil surface) are developing.
“At around 12 months, post sowing, the tap root dies and the plant is dependent on the rooting structure from the stolons. This is known as the clonal phase and it is now that the plant will be actively fixing nitrogen.”
The pictures demonstrate the
early phase of clover dev-
elopment and full estab-lishment.
This year the Farm Management team at the CAFRE Dairy Unit at Greenmount campus has incorporated cl-over into a number of paddocks on the
dairy cow graz-ing block.
In late May
this year, th-
ree padd-ocks were selected based on being free of weeds, having a soil pH of 6.3 and optimal P and K status (index 2 or above). Immediately prior to sowing, two paddocks were mowed for bales and another was pre-mowed. This left the base of the existing sward open to allow for light penetration and subsequent germination.
Aberdai, a medium leaved clover variety from the recommended list, was chosen. The clover was over-sown using an Einbock seed-er with the tines positioned to create minimal soil disturbance as possible. It was sown at a rate of 6kg/ha (2.5kg/acre).
“Grazing management through the establishment phase is critical,” stresses Kathryn. She continues: “The aim is to graze paddocks at lower covers of 2600 kgDM/ha to ensure the young clover seedlings are not shaded out by the grass plants.
“Tight grazing residuals of 1500kgDM/ha will be maintained to allow light to the base of the sward. This practice will be maintained for the remainder of the grazing season and nitrogen will be applied at only half rate (12.5kg/ha or 10 units N per acre) for the remainder of the season.”
Successful incorporation of cl-over into grazing swards is part of a long-term strategy to reduce fertiliser usage on the Greenmount Dairy Unit. It will take a number of years to get clover established in all the paddocks and delivering to its full potential but the journey has begun.
If you want to discuss the potential for clover on your dairy farm, please contact your local CAFRE Dairying Adviser.
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