Successful Regrassing (and Cropping)

Transcription

1 Successful Regrassing (and Cropping) Murray Lane, Ballance Agri-Nutrients Most RPs get tired of visiting failed crops and regrassing paddocks. Farmers must also tire of spending money for no or marginal return. There are some key elements that need to be addressed to successfully regrass and grow crops, including pasture crops. These include: Controlling the perennial weeds (prior to sowing crop) and annual weeds (in crop). Ensuring pests are known and controlled springtails, cut worm, slugs, snails, and black beetle. Ensuring fertiliser is optimised. Ensuring that the soil is NOT damaged. Cultivation leads to soil structure damage affecting moisture holding capacity and enhances creation of concretions at 4-5 cm, it also affects the soil pest/predator balance leading to pest population explosion 3-4 years later e.g. grass grub. How we could do it better. 12 key points 1. Early planning Make 2-3 year plans. Pasture assessment scores will identify runout pastures. Plan to address them with a program. Decide percent of new grass (annual and perennial) you can manage over the winter. Successful Regrassing Autumn Management Field Day 1.

2 2. Think of the soil Soil is your most important resource. It is what you paid $50,000/ha for so let s improve it rather than degrade it! Soil is NOT an inert material, five billion organisms per spoonful. More soil organic matter (OM) is better, this includes soil organisms and dead roots. Aggressive cultivation destroys this over time, tending towards clods and compaction. More OM means more nutrient exchange sites, better drainage, more moisture holding capacity, more resilience to climatic effects, less compaction, better root growth. 3. No-tillage first and foremost Leaves soil resource intact. Leads to increase in soil OM, worms and soil resilience. Leaves heads on soil predators hence the balance between soil pests and predators remains intact destruction of predators leads to explosion of pests e.g. NZ grass grub. No-tillage is cheaper and effective if the rules are followed. NOTE: if we can establish the same crops with helicropping without even opening the gate why are we still cultivating? Successful Regrassing Autumn Management Field Day 2.

3 4. Drill with DAP Soil mineralisation is a key value point for cultivation. Soil disturbance leads to nutrients being released into the soil solution to support seedling development. With NO cultivation, i.e. no-tillage regrassing and cropping this does not happen. To make up for the lack of mineralisation, always drill seed with DAP at kg DAP/ha. 5. Two autumn sprays Roundup/glyphosate is an amazing herbicide, safe (dishwashing detergent is three times more toxic), effective, very broad spectrum, with no residual activity. Most crops are started with one spring spray out. This will not result in long term control of perennial weed species. Autumn sprays are required to control perennial weed species. Roundup moves with plant sap flow in the spring it is upwards to grow leaf, in the autumn it is downwards to build root strength. One autumn is better than one spring spray, two autumn sprays over a period of time will give best control. Think: how much couch is under cow pats? Has Californian thistle emerged in October? This should be part of the long-term planning process. Question: How do I fit two autumn sprays into my cropping/regrassing program. 6. A period of time with NO clover A key means of controlling microscopic clover pests called nematodes, that prevent clover seedling establishment, is to starve them. They only eat clover, so a period of time with NO clover reduces their population. Six months is good, a year is better. How does this fit into your program? When do you spray out the clover? The earlier the better. You will be paying for the new clover genetics when seed is bought. Give it a chance to establish by controlling key establishment pests nematodes and clover root weevil. Starve them out prior to sowing. Successful Regrassing Autumn Management Field Day 3.

4 7. Correct endophyte Endophytes were identified in ryegrass in the 1980s, along with their animal toxins (heat stress and staggers) and insect protection toxins for controlling black beetle, Argentine stem weevil, root aphid etc. The novel endophytes you buy in today s seed are not as robust as the naturally selected wild type endophytes of the past, however they are not animal toxic. Because they are not animal toxic, there is a great risk that over grazing in the summer will occur, leading to a weakening of the pasture, weed ingress etc, unless managed to prevent this. Endophyte fungi dies in the seed, in the bag. Last year s surplus seed has to be coolstored if it is to be useful the following year. Legally 70% of the seeds in a bag of endophyte seed have to contain LIVE endophyte. If not, don t buy it. 8. Treated seed You are farming in the northern North Island (NNI). This is the home of African Black Beetle, a voracious consumer of germinating seedlings. The only way to target black beetle is with treated seed. The correct endophyte will support long-term control. NNI is also warmer than the rest of NZ, meaning higher populations and much larger pressure from Argentine Stem Weevil. The germinating seedling needs to be protected from both using treated seed. Successful Regrassing Autumn Management Field Day 4.

5 9. Slug bait Good cultivation buries all plant material. Any plant material on the surface is likely a home for slugs. With no-tillage, expect slugs and snails ALWAYS in the spring and ALWAYS after a wet summer. Use slug bait at the full recommended rate when no-till drilling, or if plant residue is on the surface kg N/ha in first 12 months of new grass It takes between 8-18 months for newly sown clover to produce significant amounts of clover nitrogen. Without bagged nitrogen your new pasture will be running on empty during this time. Use upwards of 200 kg N/ha in the first year of the new pasture crop. This builds resilience into both the ryegrass and the clover. Failure to graze in a timely manner could result in clover being swamped by the ryegrass hence regular rapid grazings are required. 11. Don t overgraze The new pasture crop has cost a lot. It contains fewer weeds, more palatable grasses, animal friendly endophytes, most recent clover genetics, and ideally undamaged soil structure due to no-tillage. To retain the value of your investment it has to be protected. Overgrazing in the summer months is a very effective way of reducing pasture longevity. Ryegrass pastures should be grazed no lower than 1500 kg DM/ha, then spelled to allow full recovery prior to the next grazing. Overgrazing in winter often leads to pugging. This should be avoided not only to protect the pasture crop, but also to prevent soil damage and to keep the soil on your farm. No-one wants it in the river. Stand-off pads should be utilised to protect your investment in your pasture crops. During winter special purpose stand-off pads should be used to reduce pasture damage. These same areas could be used in summer to stand cattle to protect the pasture crop on offer. Massey University work suggests that 4-5 hours is all the time that is required for a herd to graze the feed offering for the day. Subsequently they could be removed to a stand-off pad, or an area being prepped for pasture renewal / cropping with a summer fallow two autumn sprays. Successful Regrassing Autumn Management Field Day 5.

6 12. Address pests Any holes in first year paddocks will (in NNI) fill up with summer grass over summer and convert to Poa annua over winter. P. annua is a source of feed for overwintering black beetle adults. The more P. annua, the more adult black beetle survive the winter, the more healthy they are, the more eggs they lay, the more larvae there are, the quicker you lose your pasture. Black beetle larvae during December February period graze the roots of any ryegrass regardless of endophyte because endophyte toxins are NOT expressed in the roots. Fill the holes by drilling the same perennial ryegrass at lower rates in years 1 and possibly year 2. Successful Regrassing Autumn Management Field Day 6.