WET LAND

Manawatu Standard, Volume LVII, Issue 156, 3 June 1937, Page 16

WET LAND

METHOD OF IMPROVEMENT. ADDRESSES TO FARMERS. Three interesting talks on the important question of improving' wet, rush-covered country were given to the meeting of sheep farmers at Massey Agricultural College yesterday afternoon. The first speaker paved the way by emphasising the ill effects of excessive water in the soil, while the second followed up convincingly on the value of draining, the final address dealing with the eradication of rushes which, almost to a disastrous extent, kept down the carrying capacity of the land. •Mr-A. W. Hudson spoke on the effects of excessive water in the soil on fertility and plant growth. He said that while water was very necessary for the soil, too much water was definitely harmful. The earth, he pointed out, consisted of 50 per cent, soil and 50 per cent, space —that space being taken up with air or water. Under ideal conditions there should be half air and half water, but in wet country the whole space was overcome with water to the entire exclusion of air. Water-logged country could be discerned immediately on appearance, the plant life being of an unhealthy yellow nature and lacking vigour. “Roots cannot live without air any more than you and I can,” he declared, “and that accounts lor poor pastures on wet country.” Mr Hudson also referred to the effect which the excessive water bad on the millions and millions of beneficial organisms in the soil, which required an adequate supply of air. Water held up the decomposition oh organic matter, which brought abouf the nitrogeheous foods on which plants lived. To starve a plant for nitrogen and oxygen was disastrous. Another point which the speaker stressed was the economic Wastage in the spring, when growth on wet country was delayed, and in the autumn when it ceased early. Effective growth demanded warmth, and water required more heat to bring it to a warming point than any other substance; for instance, water-logged soil would take 2J- times more heat than normal soil. When there was sufficient heat the water commenced to evaporate, and in the process heat was withdrawn from the soil, leaving it half baked, but cold and clammy. Air Hudson went on to describe the influence which excessive water had on tlie stability of the soil. Normal soil was of a good structure, whereas wet soil was the reverse. Water-log-ged country only had to be fairly heavily stocked to give evidence of the fouling and, wastage of feed. A remarkable fact, lie said, was that tlie removal of the excess water actually increased the water available to the plants. In wet land the roots did not penetrate freely, but when the excess water was removed the roots were encouraged to seek a greater range of feeding penetration, and in times of drought the real value of tills was proved; it was always the pasture on soggy country which dried up first because of the lack of bacterial activity. The speaker concluded by stating that the “good old earth worm” was little seen in waterlogged country, and the activity of the worm in permeating the soil and assisting in the percolation of essential water was more beneficial than most people thought. IMPORTANCE OF DRAINAGE. Stating that the average farmer did not attach sufficient importance to drainage, Air A. J. Galpin, fields instructor, of tlie Department of Agriculture, went on to show how the carrying capacity of land could be increased by draining. He instanced one farm in the MaiiawatUo of 300 acres which in 1924 carried 5/0 breeding ewes. In that year mole-draining was commenced and continued systematically, and to-day the property was carrying 1378 breeding ewes and SO stud rams. Another farm just over the fence, where no drainage was done, consisted of 130 acres and carried 200 breeding ewes—l-J- ewes to the acre as against 4.7 on the drained property. “What I am advocating to-day,” said Air Galpin, “is , mole-draining, and we in the Manawatu do not know how good it is, nor how cheaply and permanently it can be carried out.” There were 150,000 acres in the Horowhenua, Manawatu and Oroua districts suitable for moledraining, yet he ventured to say that draining was only carried out on an average) of one acre in 200. “You can drain for a little over 10s an acre, and I will go to the length of saying that you will get better results from 10s spent on draining than from 10s spoilt on top-dress-ing,” declared Mr Galpin. • Mole-draining was not new; there were many farmers in Manawatu with a wido practical experience, and lie had , seen drains that were drawn 30 years ago still working effectively. The trouble was that the activity had been confined to comparatively few farmers.

A series of very interesting slides were then shown reproducing photographs’ which had been taken on Mr McLeod’s farm at Colyton during draining operations. Mr McLeod, said the speaker, had made a very close study of mole-draining, and he was satisfied that the system adopted was a sound one. The big factor, Mr Galpin added, was not to have too many outlets, but rather to draw a series of tributary moles into a main mole. From diagrams on the screen lie showed that on a 32-acre paddock there were only four outlets, whereas without the intersecting process 300 outlets would have been necessary. Care, of course, had to be taken at all intersections, and by illustration it was shown how the blockages at all “crossings were At the conclusion of this lecture there was an interesting discussion. Sir William Perry (Masterton) said that he could claim to be the first to introduce mole-draining to the North Island, and he appreciated the talk very much. But could the scheme of things suggested, he asked, be applied to flat country? Mr ,Galpin said that his remarks applied to the rolling in this district. Sir William went on to say that lie found it necessary to re-drain every fifth or sixth year, whereas Mr McLeod (who was present) said that he had drains on his property seven years old and working, effectively. He admitted that the rolling country made all the difference. There followed a discussion on the most effective fall. Mr Galpin considered one in six the maximum and one in a hundred the minimum. He advocated a 23-inch plug for both tributary and main drains, aiid, in reply to a question, said the safe length of a drain depended on the

nature of the country. He had seen an effective drain 30 chains long. HUSHES. Dr. Yeates, of the college staff, spoke on the subject of rushes, using interesting elides to show the various types and, more important, the effective methods of elimination. There was a popular belief, he said, that rushes grew only whore there was excessive moisture in the soil, but this was not entirely correct. They were to be found under three conditions—on wet land, on overstocked land and on sandy knobs —indicating that they, started where there was a "gap or a. lack of competition" in the pasture. The big question was, of course, elimination, and there were both indirect and direct methods. The indirect schemes were: (1) Rotational grazing as agahist overstocking; (2) top-dressing to strengthen the pasture; (3) draining and liming; and all these could and should be combined. To ta,cklc the problem in a. direct way there were also several methods —ploughing, mowing, chipping or burning—but whichever of tlvesc wis adopted it would be ineffective unless

the root of the cause was attacked. The methods would have to he followed by draining, top-dressing and a system of rotational grazing. When it had been decided to use the plough, it was essential to turn a very deep furrow so that the rushes were effectively buried. The land should be cropped for two or three years, but it was very important that subsequent ploughing should not be as-deep as the initial ploughing. The sowing shown should be carried out with strong pasture grasses, which would prevent a ■recurrence of rush growth provided, once again, draining, top-dressing and reasonable stocking were given due attention.