Chisel Plough Aids Soil and Water Conservation

New Zealand Journal of Agriculture, Volume 98, Issue 3, 16 March 1959, Page 287

Chisel Plough Aids Soil and Water Conservation

By

R. V. MAXWELL,

Soil Conservator, Department of Agriculture, Kurow

THE value of the chisel plough for soil and water conservation has been very well demonstrated on the property of Mr J. Watherston at Otiake, near Kurow. Annual rainfall in this area is about 18 in. and is badly distributed, so that droughts of several months' duration are not uncommon. Temperatures are high in summer and low in winter with numerous frosts. Frequent strong north-west winds are also a feature, and their desiccating effect further intensifies the dryness of the locality caused by the low and variable rainfall. As a result the establishment of sown crops and pastures is often restricted by inadequate soil moisture.

CONSIDERABLE run-off sometimes takes place when heavy rains follow dry spells, especially on slopes facing to the north. At such times the surface of the soil is usually baked hard by the sun and north-west winds and the plant cover is thin and open owing to lack of moisture, these conditions resulting in a low rate of moisture infiltration. Effective on Steep Country The property consists of steep ridges and sidelings as well as gently sloping terraces, and it is on the steeper country that the effectiveness of the chisel plough has been most convincingly shown. Cultivation is also impeded by large boulders, some of which are buried. Cultivation is required for pasture renewal and production of fodder

crops. Before the chisel plough was acquired a number of implements were used for seedbed preparation, which was difficult owing to the steepness and roughness of the country. The heavy mouldboard ploughs, discs, and cultivators then in use were frequently damaged through striking concealed rocks or capsizing on • steep slopes, resulting in time lost on repairs and considerable expense for maintenance of implements. The chisel plough when first used to overcome these difficulties was found so successful that it is now used, in conjunction with a set of specially designed heavy harrows, for all seedbed preparation. Outstanding features have been its stability on steep slopes and its ruggedness and simplicity of construction, resulting in more timely cultivation and a significant decrease in repair bills. The extensive use to

which it has been put and the skilled and enthusiastic manner in which it has been used have enabled a valuable appraisal to be made of its advantages, especially for soil and water conservation, when used on this type of country. Features of Chisel Plough The chisel plough can best be described as a multi-purpose cultivating implement designed in America for stubble mulch farming and the control of erosion, and resembling a conventional grubber or cultivator. The tines, which are made of specially selected and treated alloy steel to reduce breakages to a minimum, are spaced 12 in. apart, and the double-ended chisel points can plough to a depth of about 8 in. Topsoil is not turned under and only a limited quantity of subsoil is brought to the surface. Tines can be either fixed or fitted with stump-jump release attachments. A number of different points and attachments are available for special

work. Wide-angle heel sweeps and duckfoot points are used for cultivating and weedkilling, and overlap on the 12 in. rows ensures complete coverage of the area being worked. Ripper tines are also available for opening subsoil for increased penetration of moisture with little disturbance of topsoil. On hill country the soil is not turned downhill as it is when the mouldboard plough is used. Also important is the fact that the chisel plough can be used on the contour on steep slopes, where conventional ploughs can be operated only in the direction of the slope. Full advantage has been taken of this last-named feature on Mr Watherston’s property. All operations are done on the contour with the assistance of automatic tractor-mounted levels. When the chisel plough is used in this manner a series of grooves on : the contour is formed in the subsoil at the bottom of the worked ground, and these promote infiltration and absorption of water. This additional soil moisture is of considerable benefit to the subsequent crop. Wafer Conservation The . effectiveness of this moisture conservation practice was thoroughly tested in the summer of 1955-56. Though only 11 in. of rain were recorded for the 12 months from April to March and severe drought conditions prevailed, excellent crops were obtained. Two and a half inches of rain were recorded in November that year, and it is assumed that enough of this was retained in the soil to ensure a satisfactory strike when sowing was carried out in February. Cultivation . Cultivation of old grass paddocks is first begun in late autumn so that full advantage can be taken of the weathering action of frost to assist the breakdown of soil for seedbed preparation. About the previous November these paddocks are given a series of strokes with the chisel plough on the contour about a chain apart, so that rainfall received before cultivation is begun is held and stored in the soil and not permitted to run off. Though penetration in this initial stroke is not very great (maximum depth 2 to 3 in.) and depends on the hardness of the soil and density of the turf, this practice is thoroughly effective and ultimately increased soil moisture is available to benefit subsequent sowings. Soil Conservation The chisel plough system of working the soil is also valuable to prevent erosion, as the remains of vegetation are drawn to the surface instead of being buried. Here they act as protection against the destructive effect of individual raindrop splashes, reduce

scouring, and act as a mulch to reduce evaporation. Protection is also afforded against wind erosion, to which protection the roughness of the surface after working also contributes. This system of working also makes possible efficient penetration of air to the soil, a factor of considerable importance in seedbed preparation. ■ Pasture Furrowing Owing to the low and unevenly distributed rainfall, pasture furrows have been found useful in this district for preventing run-off after rain and thereby increasing soil moisture available for plant growth. Significant reductions in flooding are also possible through the use of these furrows, which are usually made with a mouldboard plough after contour lines have been surveyed at predetermined vertical intervals. Modifications made to the chisel plough to enable it to be used for this purpose have proved completely successful. Only one tine is used, fitted with mouldboard attachments for throwing the displaced turf clear of the furrow. These attachments are fitted on each side of the tine so that the implement can work both ways and the necessity for empty running of the tractor is avoided. Penetration is possible to a depth of about 10 in., giving a channel with a good water-holding capacity, especially on steep slopes where it is difficult to make such a furrow with the mouldboard plough. Contour cultivations made with the chisel plough are only about half the distance apart of those made with the mouldboard plough. The automatic tractor level used when putting the furrows in has proved entirely satisfactory. Though these furrows are usually put in on the contour, in some cases a slight fall is allowed leading away from gullies or hollows where water concentrates. This takes the water

away from these places on to drier faces where it is spread and distributed by furrows put in on the true contour. Cover Improved on Depleted Tussock Land Considerable interest has been shown in recent years in the use of machinery on depleted tussock grassland with suitable topography for the introduction of pasture species for the improvement of vegetative cover and carrying capacity. A number of different implements have been tried, including the chisel plough fitted with seed and fertiliser boxes. • Sowing is done directly into the existing vegetation, the tines making a groove or furrow into which seed and fertiliser are led by tubes from the respective boxes. Both grasses and clovers have been established successfully in this manner, including perennial ryegrass, cocksfoot, and white, red, and subterranean clovers. This work is extremely hard on implements. Bumping and jolting over tussocks and uneven ground impose a severe strain, and breakages can also be caused by concealed boulders. The rugged construction of the chisel plough enables it to stand up to arduous and testing conditions with a minimum of time lost through breakages. In particular the sturdy stumpjump releases fitted to the tines are of considerable value in country where boulders are numerous, such as the downland in the vicinity of Lake Pukaki. The chisel seeder, being a trailing implement, is particularly adapted for use with a crawler tractor on comparatively steep slopes. On this type of country sowing can be done on the contour for water conservation, as the furrows left by the tines after seeding have a good capacity for water retention. The water so held considerably benefits seedling plants, especially, in areas where low rainfall often limits successful establishment.