Sow the seed, but also have a plan

Regrassing should be part of a strategic plan, not regrassing for its own sake, according to Waikato dairy farmer Mark Hickmott. “You have to keep in mind what it is you want to achieve, whether it’s growing more grass, or flattening out rough paddocks and achieving better access,” he said.

He and his wife Phillipa milk 420 cows on their 120ha property, largely made up of peat soils. They also own a 36ha runoff across the road, on which they grew 26ha of maize and harvested grass silage last season. Milk production last season was 144,000kg of milksolids (MS) from 380 cows. Having made the decision last year to intensify their farming system, the Hickmotts built a feedpad and increased cow numbers.

“In a semi-intensive system like this, you need to be 12 months ahead of yourself in feed supplies,” Mark said. “For instance, last year’s maize harvest needs to take you through to next summer.”

Summer strife

Farming on peat also presents its own challenges. The soil is very light, but can become very wet. Pastures become threadbare through winter damage and are susceptible to pulling. But the biggest killer is summer.

“Apparently ryegrass can’t cope with soil temperatures much higher than 30 degrees C, and in summer on our black soils it will regularly get much hotter than that – so the grass just gets fried,” Mark said. In some years he estimates he will have lost half his sward as a result of those three factors.

He has been regrassing regularly as part of his farm system, using a combination of undersowing and cultivation. “Undersowing is one answer but it’s a bit hit and miss,” he said.

“When the old pasture is really burnt off you can get good results as the new grass has no competition, but undersowing in a reasonable autumn doesn’t work so well.”

So undersowing is an interim measure. Full cultivation, though more costly and time-consuming, has the added benefits of breaking up the peat soil – which can become very rootbound and produce low quality pasture – and levelling out paddocks as well as establishing new pasture.

15-year cycle

Mark used to run a 15- year cycle of cropping maize around the farm to maintain his pastures, but with all the maize now being grown on the runoff, he has moved to a new system where each year he cultivates 8ha of the home farm, putting 4ha into turnips before regrassing, and another 4ha straight back into grass. In addition, he undersows up to 12ha/year at half the full sowing rate for older paddocks which are starting to thin out but aren’t yet ready for full
cultivation.

“It’s easy for me to pick the paddocks which need total cultivation,” he said. “Peat settles and shrinks – they basically become rough as guts, and the pasture becomes very matted.”

It’s also an opportunity to introduce better grass species – though he said there’s more work to be done in developing cultivars with the qualities of greater persistency, heat tolerance and deeper root systems that will survive nonirrigated conditions.

He was very impressed with the performance of this year’s turnip crop, after disappointment 10 years ago. He would consider increasing the proportion of cultivated land he puts into turnips each year. “They are an easy way to feed 4-5kg of dry matter (DM)/ day with minimal management,” he said. “For peat soils, the turnip crop helps with compaction, with the cows standing on it to graze. Give it a light till and then run the seeder over it and it produces a good sward.”

Logistics

However, there are logistical issues that drive which paddocks he will crop. It makes sense to sow those closer to the dairy so that cows aren’t walking significant distances to graze them. Typically he has planted turnips closer to home and carried out grass-tograss cultivation in the farther paddocks. Also some paddocks are wetter in spring, so it’s not a good time to work the peat, and these are cultivated in autumn and put directly back into grass, giving the new pasture plenty of time to get established before summer.

Timing is critical when sowing the grass. Some paddocks that were sown in March have had young stock on them and have already had three grazings. Other paddocks where the seed went in later probably won’t be able to be grazed until September or October. Hickmott always puts heifers on the young grass for early

grazing as they will provide light compaction without pugging or damage to the new pasture. An important part of grassto grass cultivation is increasing soil fertility and decreasing acidity. After spraying out the old pasture, Mark applies 5t/ha of lime, which is chip-hoed, then ploughed in with a chisel plough to ensure it reaches the lower soil levels. A further

2.5t/ha of lime is added, along with a capital fertiliser dressing of around double normal spring maintenance levels, and work- ed in with a power harrow before the seed is sown. With four passes of the machine it’s an intensive process, but there are no shortcuts. The actual amounts of fertiliser used will depend on soil types.

“Don’t be miserable with your fert, as farmers invariably are,” he said.

He uses Gavin Grain as a contractor rather than doing his own regrassing, saying he couldn’t match their cost. He recommends farmers make use of their local seed merchant – “Get them to come and have a look and give you some options, then you can make your own choices”.

He uses a clover-ryegrass mix but said that he doesn’t get too hung up on individual brands.

Published courtesy of Dairy Exporter - September 2009