Conserving Soil Moisture in the Orchard

New Zealand Journal of Agriculture, Volume 73, Issue 6, 16 December 1946, Page 510

Conserving Soil Moisture in the Orchard

By

J. E. HUME,

Orchard Instructor, Tauranga.

CONSERVING soil moisture is a phase of orchard practice of great importance and has, a far-reaching effect on the trees. Not only does it influence the.size and quality of the present season s crop, but it has a considerable effect on the ensuing one. Much of .the plant food that has been built up in the soil may be lost to the plant if the soil moisture is. allowed to fall rapidly or over long periods, particularly if the weather is hot and dry.

IN orchards where clean cultivation is practised, light harrowing should be carried —just sufficient to-keep the -surface free of robber weed growth. Where possible trees should be - mulched with some suitable material such as old stack bottom. The soil should never be cultivated deeply in dry weather; nor should the surface be left uneven, as that tends to.expose a greater area to the drying effect of sun and wind.

Where the orchard is in .permanent grass and cultivation is carried out only round the 'trees, mowing of the grass should be at frequent intervals during dry weather to reduce the transpiration of moisture, which may be seriously lessening the supply avail ■ able to the tree roots. Moisture conservation is also assisted by leaving each alternate mowing where it falls; to some extent that , protects the roots of the pasture from the effects of .the dry weather, and at the same time helps to build soil fertility. Mulching round the trees in dry weather, with some quick-decaying vegetable matter is recommended, provided it contains no resinous substances likely to build up in ■ the soil and become toxic to the trees or harmful “to the beneficial soil bacteria.

Do not put mulch material right against the butts of the trees, as that contact may lead to bark troubles that are difficult to con-

tvol. Always keep at least a 3in. air space round the bases of. the trees.

If weed growth has got out of hand during dry weather,. it ‘is better to mow it first and then skim cultivate rather than deep cultivate in an endeavour to turn it in all in one opera--tion. Cover Crops for Humus

’ Increase the humus content of the ■soil by turning in cover crops. Blue lupins, partridge peas, and red clover (all legumes), oats, black'barley, and mustard are suitable. Seedings should be made not later than mid-March except in the case of mustard, which can be sown as late as mid-April. Approximate seedings to the acre are: .Lupins and peas 2 bushels, oats and black barley 60 to 801 b., mustard and, red clover 6 to 81b. ..- Though crops can be z seeded earlier to suit convenience and local conditions, care must be taken not to sow a crop so early that it becomes a competitor with the trees for moisture, particularly in hot, dry weather. Manuring these crops with serpentine superphosphate, . 2cwt. an acre, is recommended.

In orchards where the surface is permanently grassed a topdressing with the same amount of fertiliser will stimulate the development of \goodtype. grasses and help to suppress weeds and poor-type grasses. . -iniLL__iuir-|.Um7T IJWWJTir.'.'F"