TREATMENT OF SOILS.

New Zealand Herald, Volume LXIII, Issue 19383, 19 July 1926, Page 12

TREATMENT OF SOILS.

GARDENS IN THE SUBURBS. 4 THE USE OF FERTILISERS. AN INTERESTING LECTURE. A lecture on "Soils and Fertilisers for Suburban Gardens" was given under the auspices of the Workers' Educational Association and the New Zealand Institute of Horticulture by Mr. R. W. Roche, in the old Grammar School building, on Saturday evening, Mr. N. R. W. Thomas, secretary of the institute, presided. Mr. Roche described the different types of soil in the neighbourhood of Auckland, from the very light volcanic type at Mount Eden to the intractable clay in parts of Ponsonby and Remuera. Dealing with clay soil, Mr. Roche said that after being dug it must be left to the influence of the weather for a time, and should then be given a dressing of quicklime. The lime counteracted the. acidity of the soil, made it easier to work, and stimulated the bacteria which extract nitrogen from the soil,

After a time a crop should bo sown for green-manuring. The leguminous plants were among the best that could be sown as the bacteria which extracted nitrogen from the air existed on their roots. Another good crop was oats, which should bo dug in when about 2ft. 6in. high. Blue or white lupins were good for the purpose as were also vetches. Ir« treating clay soils it was impossible to trench in tha usual way by bringing up the subsoil to the surface, as the subsoil was unsuitable for plant growth, but the top layer of soil should be taken off and then the bottom of the trench so formed should bo thoroughly loosened. This allowed for drainage of the soil.

The treatment of volcanic soils was much the same as that for clay soil, although for different reasons, said Mr. Roche. Limo assisted in compacting a light sandy soil, while humus enabled it to retain mositure.

Turning to tho question of manures, the lecturer said that nitrogen could be supplied to plants in either organic or inorganic forms. Inorganic nitrogen was obtained in the form of sulphate of ammonia or nitrate of soda. The nitrate would prolong the life and delay the maturity of plants.' If the season were short and the weather hot so that plants were maturing rapidly, they should be given nitrate. If the season were long and wet the phosphate should be given to hasten maturity. Mr. Roche then described the various animal manures, which contained nitrogen, and outlined the different manures from which plants could obtain prosphoric acid. Referring to potash manures he said that care should be exercised in treating different crops, as some potash manures contained chlorine, which was injurious to certain crops. The only form of potash which could be used for potatoes was the sulphate. The chlorine in the other forms would make the tubers waxy and watery. The sulphate promoted the deposit, of starcb in the tubers, strengthened the stems, and helped the plants to resist disease. At the' conclusion of the lecture a number of questions were asked, and a hearty vote of thanks was accorded.