Rural Diary November 2019

New pastures are a great opportunity to lift production and fine tune the production dynamics on your farm.

After sowing your new pasture paddocks, ensure you monitor them as they emerge. Once the clovers are at the two trifoliate stage, it is a good time to assess the weed pressure. Some paddocks can be clean during establishment but many have a resident weed population that emerges at the same time as sowing down the new pasture. Checking the paddock at this early stage allows selection from a range of herbicides that can prevent the weeds competing for nutrient, moisture and light.

Weeds are much easier to control when they are small, so once your clovers have got two trifoliate leaves, check the paddock for weeds. Identifying the weeds at this early stage can be tricky but I  recommend a copy of “A Guide to the Identification of New Zealand Common Weeds in Colour” by E. A. Upritchard. This little red book is a good investment to have in the truck, and shows the most common weeds at the seedling stages. Identification of weeds is required so the correct herbicide can be selected.

A couple of common weeds seen in new pasture are shepherd’s purse and spurrey/yara. Both these weeds have distinctive characteristics. The shepherd’s purse seedlings have distinctive white hair on their leaves in a cross shape, these can be seen with a hand lens. Spurrey/Yara is an interesting weed, the seedling has upright, round leaves which can be mistaken for grass, but it has a distinctive pattern of four upright leaves originating from the stem above ground level. As with many weeds, spending time to get to know them helps with identification. I suggest if you would like some help identifying weeds, contact your local PGG Wrightson Technical Field Representative.

Weeds in pasture often show up where the gaps are. If you have used weed control and left open areas, use some more seed to fill in those gaps and prevent the weeds establishing. This can sometimes happen, even in new pastures where something has gone wrong during establishment.

If your new pastures are patchy with large gaps, consider using the drill to fill in those gaps because weeds do not provide much in the way of value feed for your stock compared to modern productive grass species. Contact your local PGG Wrightson Technical Field Representative who can help.

I am receiving an increasing number of calls from across the North Island especially the Waikato and Manawatu, about Yellow Bristle Grass (YBG) being found in both pasture and crops, and more particularly maize.

This weed is part of the family of annual grasses known as Seteria, which includes foxtails and millets. YBG originally came from Asia and has spread through Europe, North America and Australasia.Over the last few years, possibly driven by wet winter pugging,

YBG has spread through Taranaki, Waikato, Auckland and the Bay of Plenty, moving from roadsides into paddocks.

YBG does not provide good quality late summer/autumn feed. It is a C4 photosynthetic plant that grows more vigorously at higher temperatures than ryegrass. It becomes dominant through the summer months, reducing the quality of your pasture. Then with winter frosts, the YBG dies out leaving gaps for weed and more YBG infiltration the following spring. 

Germination of YBG seeds typically starts around mid-October when soils are about 16 degrees Celsius and peaks by mid-November when soil temperatures are over 20 degrees Celsius. This is a  similar timing to other C4 weed grasses, such as summer grass, crowsfoot grass, and smooth witchgrass, however due to the size and seed numbers per plant, YBG is far more invasive and  competitive.

The seed heads can normally be seen from late December onwards, but more commonly through January and February. Once these seed heads appear, the seeds are viable and cannot be killed by sprays. Seeds are hard coated and dispersed in water,in hay, on animals and in contaminated crops such as maize. They are dormant for about three months before they can germinate. Germination is driven by soil temperature, so usually new germination doesn’t happen until the following spring. The seeds can last in the soil for up to ten years, although generally only viable for just a few  years.

Because YBG and other weed C4 grasses readily invade run-out or pugged pastures, the best form of control is not to get into the situation in the first place. Avoid allowing flat weeds to dominate and then spray them out, as this leaves a bare patch in the pasture for weeds including grasses to invade.

Top control tips

• Learn to identify YBG and how it differs from other summer grasses, especially at the vegetative growth stage. One of the most recognisable features of YBG is a bright red stem base. Once identified, you can then isolate the area and treat accordingly.
• Avoid pasture damage at the key germination timing, from October to December.
• Remove seed-heads through topping during the summer or tight grazing before the seed-heads appear. Seeds pass through the rumen and land on the ground in a pile of dung ready to germinate the following spring.
• Spray non-selective herbicide, such as glyphosate, before seed-heads are produced.
• Whether the YBG is in pasture or crop, for example maize or brassica, there are selective herbicides available that kill the YBG and other summer grasses before they go to seed-head preventing damage to your pasture or crop. Speak to your local PGG Wrightson Technical Field Representative for guidance. 
• YBG seeds can be killed in a good quality silage pit where increase in temperature and the correct acidic conditions are created during the ensiling process.

For more information on YBG control, get in touch with your local PGG Wrightson Technical Field Representative.

This is the third article of a three-part series that takes a closer look at New Zealand soils. This month, I focus on the different management strategies that are required for the four distinct soil types that were discussed in the last issue.

New Zealand soils are generally young (comparatively worldwide), made from inherently different parent materials of different origins. Soil types have varying nutrient availability and respond to applied fertiliser uniquely.

Pumice soils
Pumice soils can recover quickly from intensive grazing, and soil compaction of the topsoil is usually not a problem. However, protecting them from pugging damage is important as they can erode  easily if the pasture is exposed by stock. Cultivation should also be kept to a minimum. These soils are loose, friable, and have a low bulk density which makes them perfect for low/no till methods of planting. Pumice soils are naturally deficient in Phosphorus (P), Potassium (K), Magnesium (Mg) and Sulphur (S) and always need yearly applications of these nutrients if they are to remain  productive. Cobalt (Co) and Selenium (Se) are two trace elements that are lacking in pumice soils and need to be added to yearly fertiliser applications. 

Organic/peat soils 
These soils usually need  some kind of artificial drainage to be productive. Over drainage (drains that are too deep) of these soils can make them dry in summer. This can cause subsidence (sinking soil), poor summer growth and hydrophobicity. By keeping drains shallow and/or controlling the water table, you minimise many of these problems. As for pumice soils, cultivation should be kept to a minimum, and low/no tillage methods are recommended. These soils have high cation exchange capacities, and a naturally low pH. Accordingly, they need larger lime applications to increase or maintain pH than other New Zealand soil types. As these soils often have small amounts of mineral material, nutrient deficiencies are common, especially P and S and some trace elements.

Sedimentary soils
This soil type is the most common soil in New Zealand. It is no surprise it is comprised of many soil orders and groups. So the  management of these soils can only be described at a generic level.  Some sedimentary soils naturally provide considerable amounts of K (from soil clay minerals) for plant growth. Some of these soils are unlikely to require capital applications of K and may not even  require maintenance K applications. Sedimentary soils tend to have medium-to-low Anion Storage Capacity (ASC), and therefore require lower rates of maintenance or capital P fertilisers compared  to other soil types. Given the low ASC, they tend to be responsive to S fertiliser in the spring, especially after a wet winter. Some sedimentary soils are poorly or imperfectly drained and prone to soil damage from grazing animals. Cultivation also has to be carefully timed to avoid soil damage as these soils take longer to dry out than other soil types. Some sedimentary soils can be low in  Molybdenum (Mo) and need periodic applications of this nutrient to ensure optimal clover growth. 

Ash soils
Ash soils include some of New Zealand’s most productive soils, and have naturally good soil structure and bulk density. These soils tend to tolerate the impacts of machinery and grazing animals better than other soil types. Cultivation still needs careful management to preserve topsoil structure, as some of these soils have limited workability when wet. Ash soils generally have naturally low levels of K, and can respond well to K fertiliser. These soils usually have a higher ASC than the other soil types, and therefore need larger amounts of maintenance and capital P fertiliser compared to the other soil groups. These soils also generally tend to have higher sulphate-sulphur levels, again due to the higher ASC.

For more information on your property’s soil type or to arrange a soil test, talk to your local PGG Wrightson Technical Field Representative.

The warmer months are an exciting time in the garden as your spring planting efforts come to life, There is also plenty of summer sun loving crops to plant and it's the perfect time to get your garden into shape for summer BBQs and backyard entertaining. 

By now your spring planting should be coming to fruition and you can enjoy bountiful harvests of homegrown vegetables. Harvesting your vegetables regularly helps promote more growth throughout the season. Crops that flower and then fruit will continuously fruit throughout the summer season if you keep up with harvesting and watering.

There is still plenty to plant at this time of year, so you can continue harvesting delicious homegrown ingredients for your favourite summer meals. Pizzas are a great option for feeding family and friends over the summer entertaining months. Plant tomatoes and a variety of herbs and you'll have tasty, fresh pizza toppings. Top tomato varieties for pizza include Money Maker (reliable and flavoursome), Beefsteak (large and tasty), Grosse Lisse (full of flavour) and Sweet 100 (small and sweet). 
Flavoursome herbs include parsley, thyme, oregano and basil. Rosemary can also be chopped finely and added into pizza dough for extra flavour. Herbs will provide the perfect finishing touch to your homemade pizzas. If you're planting your tomatoes in the garden or in pots and containers, add a layer of Tui Tomato Mix, which is specifically formulated with extra potassium to encourage a bumper crop of big juicy fruit. Plant your herbs in a spot close to your kitchen so they are easily accessible, and add a layer of Tui Herb Mix, rich in nitrogen to promote green, leafy growth and continuous harvesting.

If summer BBQs are your go-to, plant salad greens such as mesclun, spinach, lettuce, rocket and spring onions for fresh ingredients at your fingertips. Other vegetables and herbs you might want to add to your summer dishes include radish, cucumber, tomatoes, sweetcorn, basil, coriander, parsley, radish and mint. Before planting dig in organic matter to your soil such as Tui Compost to replenish nutrients used by previous crops. Compost is also an excellent water saver, it improves the soil by increasing moisture holding capacity, particularly in sandy soils. You can then add a layer of Tui Vegetable Mix, formulated with the right blend of nutrients to provide your vegetables with the best possible start and sustained growth throughout the season.

Add some vibrancy to your backyard space with some luscious green foliage and pops of colour. For greenery plant Chatham Island Nikau Palms, New Zealand's only native palm tree. They are fast growing, tolerate the wind, dry summers and poor soils. Gardenia and Hibiscus will bring a relaxed tropical feel to your garden. They both make excellent container plants, choose a large container and plant with Tui All Purpose Potting Mix, specially formulated to give the best start to your indoor and outdoor plants in pots, containers and hanging baskets.

Plants use nutrients from the soil as they grow, so replenishing the nutrients used by your plants ensures they will grow to their full potential. Feed your plants with a suitable fertiliser during key growth periods and remember to water your plants in the morning or evening to avoid water evaporation. A good deep soak every few days is better than shallow watering every day as it helps plants to better survive short term drought.

For more information, pop into your local PGG Wrightson store.