Pacific Planters'

Digest

Analysis Of Soil

Samples

FARMERS interested in sending soil samples for analysis should contact the chemical laboratory to which the sample is to be forwarded before posting it.

Many laboratories prefer soil samples to be accompanied by in formation on reasons for requesting analysis, details of crops previously grown in the soil, livestock used, fertilisers used and so on.

Sampling should be carried out within areas of approximately uni form soil. Former tree sites, post holes, burnt stumps or areas where rubbish or timber has been burnt should be avoided.

If more than one soil type occurs within the area, each soil type should be sampled separately. This also applies to areas which appear to have

the same soil type but which show differences in the growth of plants.

Both areas should then be sampled to permit comparison of results.

Usually only the first foot of soil is sampled since this is the horizon from which the plants draw most of their nutrients, and which is most affected by fertiliser treatments.

Samples should be taken with a post-hole auger or similar implement.

At least 10 sites representative of the plot or area to be investigated should be sampled.

First remove any undecomposed plant material, then take samples from the 0-6 in. layer and mix the 10 samples together on a piece of canvas or sacking. From the mixed sample take a “grab” sample, i.e., spread the material in a layer, then take small portions at random so that the sample taken (1 to 2 lb) is repre sentative of the soil from the 10 sites.

Place in a calico bag, tin or other container. This method of sampling should then be repeated for the 6-12 in. layer, or other layers if required.

If possible, dry the samples in the sun before consigning.

The Benefits Of

Mulching

MULCHING is the application of certain materials to the soil to conserve soil moisture and it has decided benefits in tropical areas which experience long dry periods.

Mulching lowers soil temperature and reduces evaporation of moisture.

It also keeps down weed growth and maintains the soil in a loose, friable condition which, in turn, lessens the need for cultivation.

Mulches also break the force of raindrops, and steady streams of water which can be most destructive to the granular condition of the soil.

Mulches may be composed of a wide range of materials, but those of a loose, open character are generally the most satisfactory. Of these, the organic materials are the most prac ticable. Most 'of these have the added advantage of improving the condition of the soil if dug in at a later stage.

Composts, animal manures, lawn clippings, straw, wood shavings and sawdust, are but some of the

materials which may be used to good advantage for mulching. Straw, wood shavings and sawdust should be re moved at the end of the season and not incorporated with the soil.

Mulches with nutritive properties, such as animal manures and com post, enrich the soil slightly with the leaching of soluble plant food.

Most plants could be mulched to some advantage but preference might be shown for those planted wide apart, shallow-rooted plants and those which require a good deal of water.

Nutritional Deficiencies

In Coffee

A PRELIMINARY survey con ducted by the Department of Agriculture in Papua-New Guinea has shown that many coffee planta tions do not appear to have adequate or balanced nutrition. The findings of the survey are of interest to all coffee planters in the Islands.

The main conclusions are:— © Potassium deficiency is probably responsible for low yields on many plantations. • The potassium - magnesium balance is very critical. Use of too much potassium without magnesium induces magnesium deficiency, and this deficiency is quite common. • Sulphur deficiency exists in many areas and is often responsible for poor early growth. Sulphur should always be added in fertilisers at least once a year. Nitrogen added without sulphur will aggravate sulphur deficiency. ® Outstanding early growth is usually associated with a high soil phosphorus status. • Nitrogen deficiency occurs on some plantations where shade or fertiliser is not adequate. • Some trace element deficiencies probably exist. Zinc and iron deficiencies are widespread; boron deficiency has also been indicated. • Mulching is an advantage in all

areas but more particularly in the drier areas of the Eastern High lands.

Leaf analysis is accepted as being the most useful tool for the diagnosis of deficiencies in coffee and for the evaluation of fertiliser requirements, according to the P-NG Department of Agriculture. The department has equipment and facilities for carrying out comprehensive leaf analyses, and subject to staffing can provide these analyses rapidly.

Leaf analysis shows whether the essential nutrients are being absorbed in sufficient amounts for optimum growth and yield, and will indicate whether the present fertiliser pro gramme is adequate or whether it should be modified.

Value Of Copper

For Pigs

INDICATIONS are that higher than normal levels of copper, as a sulphate, carbonate or oxide, improve the growth rate and efficiency of food conversion of growing pigs.

All animals require copper at trace levels, and copper with iron is necessary for haemoglobin forma tion.

Usually sufficient copper is present in tropical soils since the amount required is very small, but more deficiencies than would be expected do occur, with the result that pig growth is affected.

For pigs, 10 parts per million of copper in the diet is considered adequate as a trace mineral require ment. This compares with the 125 or even 250 ppm (1 or 2 lb of copper sulphate per short ton) recommended as a growth stimulant for growing pigs.

In Britain research workers have almost invariably reported improved performances with high levels of copper. In trials carried out at 36 different centres, growth conversion was improved by 7,9 per cent, following the inclusion of 2 lb of copper sulphate in each ton of food.

American workers, however, stress the toxic effects that may occur at this level and suggest that 100 parts per million is the safe upper limit.

In Australia varying results have been received with copper intake experiments, and at this stage further research seems necessary before the pig farmer in the Islands will be able to gauge to what extent his stock will benefit by any copper additive.

In the meantime there may well be ways of improving performance by better husbandry and feeding which will yield greater returns.