In a nutshell...
- The soil is the basis of all farm productivity.
- The soil is where you start planning your sustainability programme.
- New Zealand has a wide range of soil types (more than 1000), and it's important to know what kind of soil you have.
- NZ soils are formed from a diverse range of parent materials, ranging from old sedimentary rocks to recent volcanic ashes. These vary greatly in texture and natural fertility.
- Generally New Zealand soils are low in nitrogen (N), phosphorus (P), Potash (K) and Sulphur (S).
- Good soil structure consists of aggregates ranging from crumb to nutty. These must be maintained as they are the basis of air and water flow around plant roots.
- This will also allow the bacteria in the root nodules of clovers to fix nitrogen from the air at no cost to the farmer.
- A healthy soil also maintains a massive number of micro- and macro-organisms (bacteria, fungi, protozoa and earthworms).
How can you tell if you have a problem?
- Poor pasture growth over the whole season.
- This is most noticeable when the spring flush which does not occur.
- Lush pasture growth around dung and urine patches which stand out clearly.
- There is very little ryegrass present - the ideal is 70%.
- There is very little clover present - the ideal is 30%. What clover is there is weak.
- The pasture is made up of poor plant species, most noticeable in summer.(See Pastures)
- There is a very high incidence of weeds. (See Weeds)
- Some farmers (See Organics) are not concerned about many of these weeds as stock eat them and they add variety to the diet.
- There are large bare patches in the sward.
- The pasture is being pulled up in clumps by the stock while grazing.
- There are patches where the pasture is dead. Likely to be insect damage. (See Insect pests)
- The pastures "poach" or "pug" (form mud) easily when grazed during wet conditions.
- Compacted layers form within 200mm of the soil surface.
- Water ponds (forms puddles) on the surface after rain.
- Pastures do not last and large parts of the farm have to be resown each autumn.
- Leaching of nitrates into the ground water.
How can you tell if you're doing well?
- A soil profile showing plant tap roots going down below 200mm.
- The soil can be broken by hand into good crumb and nutty structure.
- More than 2-3 earthworms for each spade spit.
- Soil to smell pleasantly "earthy" and not sour.
- A green leafy sward with good growth rates (DM/ha/day) all the year round.
- Good spring flush with growth over 100kg DM/ha/day.
- Healthy grass and clover in a 70/30 proportion.
- No low productivity species.
- No weeds and no areas of bare ground.
- Dung and urine patches are not prominent and do not show for a long time.
- No dead areas of pasture due to insect damage.
- No pulling of pasture.
- No pugging when wet.
- No puddles during wet weather, or if there are they do not persist.
- Pastures last for many years and no need for regular renovation.
What can you do to improve things?
- Have regular farm walks to check pasture growth.
- Be aware of the pasture growth pattern for your particular farm.
- Regular soil test (2-3 years).
- Carry out recommendations by fertiliser consultant to keep soil nutrients at optimal levels for your soil type and farming system.
- There is no point in putting on more that is needed.
- Don't forget lime. It's not strictly a fertiliser but low pH will limit fertiliser utilisation.
- When applying fertiliser, avoid runoff and loss of nutrients into the air.
- Do not spread fertiliser right up to the edge of streams.
- Keep a vigorous clover content (minimum of 30%) to exploit the free nitrogen from the air. This can be the equivalent of around 230kg N/ha/year.
- Plant new pasture species and appropriate cultivars for soil type and production potential.
- Prevent pugging during wet weather by removing stock from pasture.
- Aerate or subsoil paddocks (especially on dairy farms) to repair compacted layers.
- Fence off waterways and prevent stock grazing up to the edge of waterways.
- Develop riparian strips and wetlands to reduce chemical pollution of waterways and also to act as sediment traps
- Do not let stock drink out of waterways. Provide water in troughs.
- Don't have day and night paddocks to prevent fertility transfer.
Where can you go for help?
- Regional Councils
- County Councils
- Federated Farmers of NZ
- Ministry of Agriculture and Forestry
- Department of Conservation
Dr Richard Chapman, Soil Consultant. Phone (07) 829-5437