STUDIES OF RESPONSE TO FERTILIZER NITROGEN

The effects of 59, 118 or 177 kg N/ha were measured on 7 occasions from 8 to 57 days after application to a perennial ryegrass sward in terms of changes in composition. The first increase Dt of N significantly raised percentages of CP, non-protein N, K, P, Ca, Na and Mg and significantly depressed percentages of DM, OM and OM digestihility. The second increment of N resulted in a further rise in the percentages of CP, true protein, non-protein N, K, P, Ca, Na and Mg; the percentages of DM and OM were further depressed but OM digestihility was not significantly depressed. Percentages of P and Na showed increased responses for the more mature herbage; while percentage non-protein N showed a more marked response in younger herbage. As herbage matured percentages of OM and Na rose, the latter only from days 16 to 45. All other attributes showed falling percentages to levels which could be inadequate for a 500 kg dairy cow yielding 15 kg milk. CP percentage reached this critical level (1.4% N) at days 37, 45 or 56 given 59, 118 or 177 kg N/ha; P percentage became critically low (< 0.36%) at days 27, 35 or 38, respectively; Mg percentage fell to the critical level (0.12%) at days 23, 35 and 46. Na percentage showed the reverse trend, being deficient (< 0.13%) in the earliest samples and becoming satisfactory from days 23 or 27 at 118 and 177 kg N/ha but it remained inadequate at 59 kg N/ba.     

Some enzyme and respiratory activities of tropical soils from new hebrides

Activities of invertase and amylase and respiratory activities of samples of 11 soils from New Hebrides were determined. The soils mostly were under forest and were acid with medium to low C/N ratios. Invertase activities were rather low but amylase activities were similar to those found in New Zealand soils. The ratios of invertase to amylase activities were mostly low.O₂ uptakes mostly responded markedly to glucose. Most values of respiratory quotients were about 1.0. Most, but not all, dehydrogenase activities were strongly related to O₂ uptakes. On an organic C basis, these respiratory activities declined with the depths to which the soils were sampled.Biochemical activities were mostly similar in forest soils derived from basalt and from andesite. Invertase activities were lower in soils under forest than under grassland covers.All biochemical activities were correlated significantly with contents of soil moisture and organic C, less with numbers of aerobic bacteria, and negatively with soil pH. On an organic C basis, none of the biochemical activities was significantly correlated with either soil moisture content or pH.     

The abundance of Trichoderma propagules and the distribution of species in forest soils

Propagules of Trichoderma generally formed less than 3 per cent of the total fungal propagules in a variety of forest soils in the southeastern U.S. and Washington State. The largest populations were found in the F and H organic horizons of the forest floor or under conditions of excessive moisture. T. viride Pers. ex S.F. Gray and T. polysporum (Link ex Pers.) Rifai were largely restricted to cool temperate regions; whereas, T. harzianum Rifai was characteristic of warm climates. T. koningii Oud. and T. hamatum (Bon.) Bain, were the most widely distributed species aggregates and were found in all the climatic regions investigated. Under conditions of excessive moisture, strains of T. hamatum and T. pseudokoningii Rifai were the dominant forms.     

Isolation and characterization of Thiobacillus from alkali soils

Alkali soils are poor in sulphur-oxidizing bacteria. By appropriate enrichment, two bacterial strains resembling Thiobacillus thiooxidans and T. novellus have been isolated from an alkali soil. The strain of T. novellus possesses characteristics which make it suitable in reclamation of alkali soils by sulphur amendment.     

Noise control activities of the state OF California

This paper deals primarily with state activity in the field of noise control. It covers motor vehicle noise, aircraft noise, noise and land use planning, and includes a discussion of what areas for future state legislation are left uncovered by federal preemption under the Noise Control Act of 1972. With regard to motor vehicle noise, California has been enforcing existing state laws that pertain both to sellers of new vehicles and to operators of all vehicles. The enactment of the Noise Control Act raises questions as to the continued legality of the existing new vehicle laws. California's aircraft noise regulations went into effect in December 1972. As a practical matter, full enforcement must await the satisfactory performance of the monitoring systems, none of which have been fully approved. The airlines have sued the state to invalidate the regulations. The outcome may well depend on the decision of the United States Supreme Court in Burbank v. Lockheed, that court's first aircraft noise regulation case, which was scheduled to be argued in February 1973.     

A NEW GRAZING SYSTEM FOR BEEF CATTLE—THE TWO FIELD SYSTEM

A new simplified grazing management system has been devized for spring- or antumn-born calves scbednled for beef production at 18 months of age on a grass/cereal system. The new system which can be conveniently described as the two-field system obviates the need for paddock fencing and paddock water installations, is simple to operate and is giving results in terms of liveweight gain performance and stocking rates per acre which are comparable with those from paddock systems. The new system employs the old practice of set-stocking. Two fields are used, however, and these are alternately set-stocked and cut for silage, or vice-versa. It has been found that by using N fertilizer to the same extent as in intensive paddock systems, i.e. around 250–350 units N/ac, it has been possible to achieve similar stocking rates/ac and performance has been unimpaired. No bealth upsets have occurred as a result of applying fertilizers on fields in the presence of grazing cattle over a period of four years at two centres, Jealott's Hill and The Leaths, in trials involving hundreds of beef cattle and dairy cows. This new system of grazing management for beef cattle is now well proven and can now be recommended to farmers as an alternative to paddock grazing.     

A COMPARISON BETWEEN A PADDOCK SYSTEM AND A 'WYE COLLEGE' SYSTEM OF GRAZING FOR MILK PRODUCTION

Two grazing systems, a paddock system and a ‘Wye College’ system, were compared in two 20-week experiments nsing 16 and 20 spring-calved Ayrshire cows in 1970 and 1971, respectively. A sward of S23 perennial ryegrass was used, and an average of 342 kg N/ha (305 lb N/ ac) was applied per annum. The paddock system had 28 separate paddocks; one paddock was grazed each day in rotation and occasionally topped in mid-season. The Wye College system had 4 plots of equal size and the cows were offered 1/7 of one plot each day; no back fence was used and surplus herbage was neither cut nor topped. The stocking rate on hoth systems was 1 cow per 0.20 ha (0.49 ac) in 1970 and per 0.16 ha (0.40 ac) in 1971. The mean daily milk yields per cow on the paddock and the Wye College systems were 16.2 and 15.3 kg (35.7 and 33.7 lb), respectively, in 1970; and 18.1 and 18.4 kg (39.9 and 40.6 lb) in 1971. The average annual output of milk was 13,500 and 13,150 kg/ha (1200 and 1170 gal/ac) on the paddock and Wye College systems, respectively. The fat and solids-not-fat (S.N.F.) contents of the milk were not significantly affected by the grazing system. It is concluded that the Wye College system was as effective as the paddock system in producing a high output of mUk per ha, but at a lower cost and with far fewer management decisions.