Soil fertility for lifestyle farmers

Buying a lifestyle farm is pretty easy - provided you have the funds. Turning it into a successful, rewarding and perhaps moneymaking venture is more difficult. Lifestyle farmers are faced with many of the same challenges that experienced, full-time farmers have to deal with. Yet pressures of time and the small scale of their operation may mean they don't have access to the same resources available to professional farmers.

However, by getting to grips with some farming fundamentals, lifestyle farmers can do a great deal to improve the quality of their land, the health of their animals, and their own satisfaction in a job well done.

One of the most important factors driving farm productivity is soil fertility. Yet for many people it is also one of the most difficult to come to terms with - you can't see soil nutrients, but you can see when pasture is not thriving because of problems with soil fertility.

Fortunately, there are some relatively straightforward ways of dealing with soil fertility problems - it just takes a bit of knowledge and a bit of planning.

First, test your soil

Soil testing is essential. There is no way that you can take effective, economically sound action to address soil fertility problems if you don't know what your soil nutrient levels are in the first place.

Soil testing is also easy. All you need is an auger, a soil sample bag and a way of recording what you have done. The auger should be one that samples to 75 mm depth, assuming you are checking land in pasture. Sampling with this type of auger will target the soil that is being used as a nutrient source for pasture. If you sample deeper - say with a 150 mm auger - you'll be testing soil that grass and clover won't be using. If you don't have an auger you may be able to hire one from your local rural merchant.

The soil sample bag is best obtained from a professional soil-testing laboratory like Hill Laboratories (www.hill-labs.co.nz) or New Zealand Laboratory Services (www.nzlabs.co.nz/). The way you record your sampling strategy is up to you - notebook or ibook, it doesn't matter, as long as you keep the information somewhere safe and refer to it in the future.

Before pulling on your boots and striding out to take the test, have a good look at your land. Is it all relatively similar - say, all gently rolling or flat? Do you have some areas that you use for one purpose and others that are quite different - say, part of the farm is used for rearing stock and part used for growing a feed crop? If the answer to either of these questions is yes, then you'll need to take two samples, one for each of the areas. Most lifestyle farms are fairly homogenous, though, and one sample will probably do.

Now identify the exact area on the farm where you are going to sample. You want to be able to take 15-20 soil cores with your auger, and you want them to be from a part of land that is representative of the whole farm. That means staying right away from areas where nutrient levels are atypical - don't ever sample near gates, fencelines, stock camps, around water troughs. Do this and you'll get an artificially high reading for your soil fertility, which means you won't put on enough fertiliser and your land will suffer. Similarly, don't sample within three months of applying fertiliser - again, you'll get artificially high results. Pick a starting point, take a soil sample, put it in the bag. Walk 10 or 20 paces, take another sample, put it in the same bag. Repeat until you've taken 15-20 soil cores. Follow the instructions on the bag for submitting it to the lab. Record your soil sampling strategy so that when you sample next year, or in two years' time, you can take samples from the same place.

One soil test gives you a snapshot of the nutrient status of your soil. To get a complete picture of the nutrient flux on your land, it's important to soil test regularly and to record this along with other information about your farm management and production. That way, you'll be able to identify how changing one part of your farm operation affects other parts.

Interpreting the results

Soil nutrient laboratories can do in-depth analysis of your soil, but the key criteria you need to start with are soil pH, the level of phosphorus (shown as Olsen P), potassium, magnesium and soil sulphur levels (sulphate sulphur and organic sulphur). These are the major factors that are likely to limit pasture production.

Nutrient

Test 

Sedimentary soil

Ash soil

Phosphorus

Olsen P

20-30 

20-30

Potassium

Quick test K 

 6-8

7-10

Magnesium 

Quick test Mg 

8-10*

 8-10*

Sulphur 

Sulphate S 

10-12

10-12

 

Organic S 

15-20

15-20

pH

 

5.8-6.0 

5.8-6.0

Table 1: Target soil test values
*These levels are for optimum pasture growth. To protect against animal health problems, aim for magnesium levels of 25-30.

Choosing the right autumn fertiliser 

If your soil test results come back showing less than optimum levels of any of these nutrients, then it is time to apply fertiliser. The best way to decide on which fertiliser you need is to take your soil test results down to your local rural merchant. Staff there have been trained to offer fertiliser advice, and if they have any problems they can always ring their local Ballance Agri-Nutrients representative, who can help out with specialist knowledge.

If soil pH is too low (i.e., if the soil is too acid), then it needs to be raised with an application of lime. Doing this will help increase the availability of key nutrients such as phosphorus, so pasture production will improve. To raise soil pH by 0.1 unit requires 1 tonne lime/hectare, and it will take around six months to act.

If soil pH is all right but sulphur and phosphorus levels are low, then a product like Ballance Superten will be ideal. On a sedimentary soil it will take 52 kg superten to raise the Olsen P level by one unit; on an ash soil it will take 113 kg superten to have the same effect.

If magnesium levels are low and you have breeding stock on farm, you should look at addressing this problem. Raising pasture magnesium levels with a product like Ballance Pasturemag is one approach, but if levels are very low then land may need to be dusted with a special magnesium product like Calmag. Seek advice about this. If animals have insufficient magnesium intake before and after calving or lambing, they can be susceptible to grass staggers and milk fever.

If your soil nutrient levels just need general maintenance, then NutriGro is likely to be your best option. This product has been designed especially to meet the fertiliser requirements most often encountered on smaller properties.

Most fertilisers that are suitable for use on lifestyle farms are available in 40 kg bags, which makes them easy to transport and use on-farm. Rural merchants such as RD1, Farmlands, PGG Wrightson and CRT can assist with the supply of a wide range of fertiliser products.


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