ROTATIONAL GRAZING.

Otago Daily Times, Issue 20704, 30 April 1929, Page 4

ROTATIONAL GRAZING.

MORE INTENSIVE GRASS FARMING. A ' PROFITABLE DAIRYING PRACTICE. May marks the end of the main milkinj? season, and now is a -good time to make plans for next season’s work. Many farmers are at present turning their attention to schemes of intensive grass-farm-ing and the adoption of-rotationa] grazing practices. The general principles underlying the practice of rotational grazing are now fairly well known. Briefly, the system consists in the close subdivision of the grassland, regulated stocking, and heavy and complete manuring. Grass is treated as a crop, the • pasture being allowed to reach a length of three inches to five inches, quickly grazed down, and then spelled till the next’ crop of young grass is ready. It is not possible at the present time to give any very definite information outlining a complete scheme for rotational grazing, for the experimental work conducted by the fields division of the Department of Agriculture this season has rather emphasised difficulties to be overcome than provided a system to be widely adopted. A certain amount of data, however, has been already collected bearing on the size of subdivisions and the intensive use of fertilisers that is of interest to farmers.

The first important point to be decided when adopting the system is the plan of subdivision and the size of the fields Wherever possible the farm should be subdivided on the plan of a central race upon which all fields open. The race should not be narrow, as cqws going to and from the milking shed churn up a narrow race badly during wet weather. A width-of one to one chain and a-half is much more satisfactory than a race half a chain wide. A wide race can be grazed and. managed as an ordinary field. In most, cases, however, there is ho necessity to reorganise the Whole internarfencmg of the farm, and the subdivision of existing fields is all that is necessary. The size of the fields is determined liy the rate of stocking, and_ it appears that the fields used for rotational grazing should be stocked at the rate of 12 to 15 cows per acre at short intervals.., A good even crass growth of three inches to four inches -in .height will. give ’ two grazing days of 24 hours each for 12 to 15 cows per acre; for, herds of 22-to 25-cows fields two . acres, and Tor herds 'of .35 to 38 cows three-acre fields arc -satisfactory. Experimental work this season has shown that when stocking at .the above rate, the subdivision of six-acre fields ..into two three-acre fields meant the - gain of a day’s grazing. . '

Before subdivision six-acre fields- were giving three days’ grazing for 37 cows, and when subdivided each three-acre field gave two days’ grazing for the herd. It is best to commence a scheme of rotational grazing gradually, making four of’.five small fields for a start, .and. treating the pasture on these fields as well-as possible. It is unwise to enter 'on. an - extensive scheme of rotational grazing until experience has been gained of the proper management of grassland under the intensive system of grass farming. , Also the practical difficulty of providing a continuous supply of feed, owing to the variation in the recovery periods of pastures at different periods of the. years, has not been completely solved - at the. present time. Some large fields which contain some rank feed are a good stand-by for grazing the herd during short droughty periods in the late spring and summer. This difficulty will probably- be got over, but whether the feed thrown by the rotationally grazed fields during short dry spells—-which may occur at any time in the spring, summer, and autumn I —should be supplemented Impartially rank growth on some reserve fields, by rank grass growth and concentrates, by grass ensilage, or grass ensilage and concentrates, can only bo solved by further experimental work. One of the most marked .features of the current experimental work ,on rotational grazing is. the very high per acre production of butter-fat from rotationally grazed fields. During the first half of this season , such fields have produced 1501 b to 2001 b of butter-fat per acre, and this is far higher. than the average production from the whole farm will be for the season. A considerable amount of work, however, 1 will have to be performed .before a suitable grazing and- supplementary feeding technique is evolved to enable dairy cows to convert all the spring, summer and autumn production of grass (except that required for hay and ensilage -for supplementary feeding) into butter-fat.

.With regard to manuring of the rotationally grazed fields, this- season’s experimental work has so far shown that late winter applications of nitrogen to heavily phosphated grassland have given appreciable increases in the early spring production of grass. The economics of these late winter applications of nitrogen are now being studied,- and should the practice prove .payable it will provide a means whereby the dairy farmer can supply young protein-rich grass for earlyca.ving cows. •