Sustainable soils and soil fertility

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.
Healthy soil also maintains a massive number of micro- and macro-organisms (bacteria, fungi, protozoa and earthworms).

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 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 are not concerned about many of these weeds as stock eats 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 groundwater.

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 consultants 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 the lime. It's not strictly a fertiliser but low pH will limit fertiliser utilisation.
When applying fertiliser, avoid runoff and loss of nutrients in 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.