Should you consider clover in 2022?
Vincent Ronayne, Teagasc Advisor Ballinrobe, notes that Clover offers an alternative to expensive artificial fertilisers and helps towards Environmental Sustainability. Incorporating clover in grassland swards can to reduce costs, improve profitability and reduce greenhouse gas emissions.
How Does It Work?
Clover fixes nitrogen from the atmosphere. Nitrogen fixation is the name of this process whereby white clover can fix N from the atmosphere and make it available for plant growth, thereby reducing the requirement for chemical Nitrogen.
Benefits of white clover
The benefits of white clover tend to occur from May onwards as sward white clover content increases. The main benefits of white clover inclusion in grass swards are:
- Increased herbage quality compared to grass-only swards in the summer months.
- Increased dry matter (DM) intake in summer and autumn.
- Higher milk production and live weight gain.
- Nitrogen fixation – white clover fixes nitrogen (N) from the atmosphere making it available for plant growth.
- Lower requirement for chemical N fertiliser application in summer.
A key requirement for the successful establishment of white clover is soil fertility. Soil fertility must be right if planning to use clover. So up-to-date soil sample results are important. Soil pH is critical. White clover is more sensitive to lower soil pH than grass. Soil pH should be greater than 6.3 and soil P & K indexes should be 3+.
The varieties to use depends on the farm system and what you intend to use the field for.
Large leaf varieties - silage
Medium leaf varieties - grazing with cattle
Small leaf varieties - grazing with sheep
Paddocks for a full reseed should be identified as early as possible in the process to avoid over-sowing clover on these. A full reseed is the most reliable method of establishing white clover and provides the best opportunity for weed control. Over-sowing is a simple and low cost method of introducing white clover into swards. Select paddocks for over sowing with the following characteristics to give the best chance of establishment
- Optimal soil fertility (index 3+ for P & K, soil pH 6.5)
- High perennial ryegrass content
- Open/low density swards – dense swards prevent light getting to new clover plant, hindering establishment
- Low weed content
Any paddocks that are not suitable for over sowing should have any issues corrected and oversow the following year e.g. improve soil fertility, lime and spray weeds.
Good grazing management is important for increased persistence and production of white clover in grazed swards. Use a paddock system where each paddock is grazed in 3 days on a 18-21 day rotation. Avoid poaching damage. Target a post grazing height of 4cm. Reduce chemical N application in the summer months.
Whether over sowing or reseeding, weeds need to be controlled before clover is established as most of the sprays for weed control on the market also kill clover.
How clover works to reduce emissions?
Nitrous oxide is one of the 3 main greenhouse gases and is given off primarily from slurry stored, slurry spread and chemical nitrogen fertiliser spreading. Incorporating clover into grassland reduces the demand for chemical nitrogen. Therefore, if there is less chemical nitrogen fertiliser spread, there is less nitrous oxide being emitted into the air. Using clover achieves a reduction in nitrous oxide by lowering the chemical N fertiliser use (up to 100 kg N/ha on dairy farms). Using clover can reduce nitrous oxide emissions by upto 40% on a dairy farm due to reduced chemical N application. Clover will help to reduce the carbon footprint of the farm and more importantly reduce total emissions on the farm.
Impact at farm level
On dairy farmers, research has shown that using clover can increase milk solids production 20-48 kg/cow per year and increase net farm profit by €108-€305/ha. On suckler farms, profitability increased by 14% for the grass/clover system when compared to a ‘conventional’ pasture system.
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