IMPROVING WET COUNTRY

Hawke's Bay Herald-Tribune, Issue 117, 3 June 1937, Page 14

IMPROVING WET COUNTRY

-Press Aasooifttion.l

Value of Mole Draining Emphasised MASSEY EXPERIMENTS

CBv Telearaph-

PALMERSTON N., This Day. Kew ira*' rosh-covered oountry and oth or inefflciontly drained eountry ean ba improred was told to tho sheepfarmers in conference at Massey College yesterday. Mr A. W. Hodson, ,of Massey College staff, explained the effect of excessivOj water in the soil on fertility and plant growth Mid the desirability of gettingj rid of nat excess water. He pointed; out that the average soil consisted of| half solid nsatter, the other half being' occupied by water and air. And of' the latter half, the ideal was once again half water and half air space or, in other words, one-quarter of the whole should be water'. Beneficial organisms in the soil required air and if there was an excess of water, then plant growth failed. The activities of nitrogenous organisms were also stifled by excess water. Another effect of waterlogging was to mahe soils "late." Excess water in the soil in the spring delayed the rise in soil temperature to that heat which enabled the organisms to become active again. It took flve times as much heat to warm water as it took to warm dry soil, so that one eould say that on an average it would take two and a-half times as much heat to warm water-logged soil. Extreme wetness also had an effect on the stability of a soil. It pugged easily and this prevented proper drainage and intensified the wetness of the land. The removal of excess water actually increased the amount of water available to the plants. That might sound a contradiction, but was brought about by the growth of a greater root system. Mr Hodson paid tribute to the work of the earthworm, which could not live in water-logged soil. Methods of Drainage. In dealing with specific methods of drainage, Mr A. J. G-alpin, of the Department of Agriculture, claimed that an area of 150,000 acres in the Mana-watu-Horowhenua district could be mostly improved by the adoption of mole-draining if proceeded with systematically. The benefits of this method of draining was yet little rcalised. Mole- drainage, ho said, was not new to the Manawatu district. Works of this nature, institutdd .30 years ago, were to-day still working efficiently. Although it has functioned so successfully, its application affects only one acre in every 200. The speaker quoted an instanee of a farm property on which this system of drainage had been carried out and of the increased returns that had resulted. The carrying capacity of sheep had shown a Temarkable increase, which was quite illuminating. At this stage, a slide was shown illustrating two adjoining paddocks, one of which was mole-drained. The same type of certiiied rye and white clover were sown in each. The latter showed a rich deep grcen sward, while 'in the untreated paddock the sward was greyish, dacking profusive growth. Much of the failure of mole-drainage was due to the intersecting mole-drain blocking those that it intersects. In order that this blockage should be effectively overcome, the intersecting drain should be drawn at a depth fully three inches deeper than those it intersects. An important feature was that the mole should be in the good clay, and the speaker regarded that two inches ' in it was sufficient. It was also eseential that depressions or hollows should .be avoided by taking the drains around them. The amount of damage caused by the tractor when drawing out the drains was negligible as it invariably healed over. Sir William Perry, who claimed that he introduced mole-drainage into the North Island, said from his experience of mole-draining on comparatively flat ■ conntry, he found that the use of a considerable number of pipes were necessary. He agreed that the system outlined by Mr Galpin for rolling eountry was both efficient and cheap in its outlay. Mr Galpin said that the whole ques tion depcnded upon the extent of the fall available as to the efficiency of the system. The minimum appeared to be 1 in 100 and the maximum was 1 in 6. On the rolling eountry, which he had referred to, mole-drains cut seven years ago were still functioning efficiently. Replying to a question relating to costs, Mr Galpin explained that, apart from the use of the plant, mole-draining did not exceed 11s per. acre. Mr Galpin submilted that this outlay, which was less than applying superphosphate, was more advantageous, especially in the early stages on a farm. Without efficient drainage the benefits of superphosphate were greatly nullified. The la,te spring was probably the best time to draw out mole-drains as the clay at this period was more sodden. Replying to another questioner, Mr Galpin quoted a farm in the Kairanga district which was one time known as the "Duck Earm." Since it had been mole-drained it had been transformed into one of the best farms for the , wintering of stock. Control of Rushea. Outlining the growth and conlrol of rushes, Df. J. S. Yates, of Massey College staff, said they were'a fype of weed, the presence of which indicated that something was wrong with ihe soil. Rushes wore undoubtedlv expeusive weeds because of the pasture that they displaced. Rush growth was to • some extent depenilent on close grazing, the opportunity that it required being afforded by the openness that resulted. Wetness, over-grazing and sandy knobs all had open pastures which enabled rushes to become rapidly established.' Important points in management were to avoid exeessive close grazing so as to leave the pasture open, top-dressing to strcngthen the pasture and draining. A further point was the sowing of brown top or lotus magor among the

.rushes. "The growth of these grasses gradually weaken the rushes. All methods should be combined in order to make an attack effective. Important reeults follow ploughing, which should be first done with a swamp-plough to a good depth. Cultivation for two years should follow, when a pasture could then be laid down. The ploughing on this occasion should not be so deep so as to resurrect the rushes originally turned in. Moledraining, liming and top-dressing could then be carried out, making the young pasture nigenous and not susceptible to invasion by TuShes. The direct methods of attack, explained Dr. Yeates, considered would be wasted efforts if the cause that let rushes in was not tackled. A concentration on strengthening the pastures , was an effort that was well worth while, giving the farmer grass instead of a waste . weed. After replying to various questions. the lecturers were eaph accorded a hearty vote of thanks.