Soil Fertility and Pasture Growth

Sears, P. D.

doi:10.1111/j.1365-2494.1950.tb01291.x

Cited by 22 publications

(9 citation statements)

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“…The results of these trials c10sely followeel those obtained by Sears (1949) as Grasslands Division, where vigorous grass seedlings were shown to causc significant los ses in c10ver seedlings, during the establishment stage.…”

Section: Ouersowingsupporting

confidence: 65%

“…At Grasslands Division it was found that as fertility and stock carrying increased, so also did the earthworm population. Sears (1949) and Waters (1955) estimated that on heavily stocked pastures the weight of earthworms in the soil approximated the weight of stock carried on the surface. Earthwcrm data were also secured at Te Awa on unimproved pasture, and on heavily set-stocked improved pastures.…”

Section: Lnsects and Earthwormsmentioning

confidence: 99%

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Pasture management trials on unploughable hill country at te Awa

Suckling¹

1959

New Zealand Journal of Agricultural Research

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Further results of trials involving oversowing, topdressing and grazing management practices on steep unploughable hill country with an original carrying capa city of about 1.5 ewes per acre, are presented.Pasture improvement has been recorded by frame measurements to determine herbage yield3, by herbage dissection, and also point analyses to determine botanical changes. With improvement in pasture, carrying capacity has increased markedly without detriment to stock thrift. All sheep were weighed monthly, and fleece weights were recorded.

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Section: Ouersowingsupporting

confidence: 65%

Section: Lnsects and Earthwormsmentioning

confidence: 99%

Pasture management trials on unploughable hill country at te Awa

Suckling¹

1959

New Zealand Journal of Agricultural Research

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“…Although too much weight should not be attached to estimates of N fixation based on pot work with clover it is noteworthy that after making allowances for the spread of the clover plants, the estimate of 493 kg N/ha in this experiment is in agreement with the field data obtained by Sears (1950) of 522 kg/ha and Armitage & Templeman (1964) of 305 kg/ha and suggesting that the clover in the unfertilized pots was functioning normally. An allowance (67 kg N/ha) was made for some nitrogen being taken from the soil (Allos & Bartholomew, 1955, 1959.…”

Section: Discussionsupporting

confidence: 86%

The effect of nitrogenous fertilizers on white clover

Low¹,

Armitage²

1970

J. Agric. Sci.

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The comparative effects of very heavy dressings of ammonium sulphate and urea on the growth of established plants of white clover (S100) have been studied in pot culture. Five applications each of 26.3 kg N/ha were applied over 9 months in 3 different ways (i) direct contact of the fertilizers with the leaves, (ii) only with the stolons or surface roots or (iii) applied 12-5 cm below the soil surface.The ammonium sulphate broadcast over the leaves reduced the growth of the clover whilst urea under the same conditions caused temporary damage with very little reduction in dry weight compared with the control. When the ammonium sulphate was applied to the soil surface or 12-5 cm below, there was appreciable reduction in dry weight but less than when the fertilizer was in contact with the leaves. Under the same conditions, urea did not reduce growth.The pH of the soil fell to about 4-6 with ammonium sulphate (control 6-1) but only slightly with urea.Root development was not affected by urea but greatly reduced with ammonium sulphate. With both fertilizers the root nodules were very pale in colour and few in number compared with the control. xTyrrpT}/-)•nTTpT'TO'Nr a n n u m as a m m o n i u m nitrate (15-5% N ' N i t r ochalk') to plots of pure white clover and found little When nitrogen fertilizers are applied to grass-effect on yield although there were indications of a clover swards, the proportion of clover tends to depression at the highest rate. The fertilizers were fall. Clovers may bo able to obtain all the nitrogen applied twice in the year with 2 cuts between they require for maximum growth from the air so applications. that applying a nitrogen fertilizer may have noIn small grass-clover field plots at Jealott's Hill effect. The grasses on the other hand depend on where the effect of ammonium sulphate, amrnon-'available nitrogen' in the soil: the greater the mm nitrate and urea applied in solution to the amount the more vigorous their growth (although plants was studied, there was least reduction in the there is an upper limit) and the greater the competi-proportion of white clover where urea was used, tion with the clovers growing with them for light, Though each treatment 'scorched' the leaves, urea space, water etc. particularly as grasses in general did so least. As there were equal weights of nitrogen are considerably taller than for example white in equal volumes of solution, the osmotic pressure clover. Some consider this competition sufficient to of the urea solution was about 33 % that of the account for the virtual disappearance of white ammonium sulphate and about 50% that of the clover with high rates of N fertilizer. There are, ammonium nitrate: consequently as plasmolysis however, some indications in the literature (Heddle, would be least with the urea one might expect the 1966) that in part at least the suppression of the smallest damage. clover may be a direct effect of the applied nitrogen.Damage to clover plants by nitrogenous fertiAs fertilizer N depresses nodulation of clover, lizers may...

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“…yield for treatment 1 for the 4-year period was taken. Although it is low for normal practice it is of a similar order to that quoted by Sears (1950) for grasses without clover (1800 lb. dry matter and 270 lb.…”

Section: Grass-clover Swards Receiving No Nitrogen Fertilizermentioning

confidence: 76%

The intensive production of herbage for crop-drying Part VI. A study of the effect of intensive nitrogen fertilizer treatment on species and strains of grass, grown alone and with white clover

Holmes

MacLusky

1955

J. Agric. Sci.

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have shown the effect of nitrogenous and mineral fertilizers in maintaining high production from grassland. Most of these experiments were based on mixed swards, in which perennial ryegrass predominated. Simple one grass-one clover leys have increased in popularity, and much interest has been shown in the so-called pedigree or bred strains of grasses. There is little published evidence on the response of these strains and mixtures to fertilizer treatments. It was, therefore, decided to follow earlier studies by comparing the performance of commercial and pedigree strains of the most important species of grass under uniform conditions of cutting and at various levels of fertilizer treatment.Attempts have also been made in previous experiments to assess the efficiency of utilization of fertilizer nitrogen by the grass sward, but it has always been difficult to decide on a control yield since this is so much affected by the nitrogen contribution from clover normally present in the sward. In the present work, therefore, swards containing no clover were studied without fertilizer nitrogen and with two levels of fertilizer nitrogen, and were compared with grass-clover swards so that an assessment could be made of the net contribution of nitrogen from the clover.The experiment was established in 1948 and continued for 2 years in 1949 and 1950 with uniform cutting intervals for all grasses and treatments, the object being to determine the difference between grasses in yield, seasonal productivity, yield response to nitrogen and compatibility with clover. It was considered that in 1949 and 1950 the fixed cutting schedule might have reduced yields on the low fertility treatment by too frequent defoliation, or on the other hand might have reduced the quality of the herbage in the highest fertility treatment because it was not cut often enough. The treatments were continued, therefore, 18 in 1951 and 1952, but for each treatment the grass was cut when it was considered to be a suitable height for grass-drying, irrespective of the condition of the same grass under the other treatments.In 1953 an assessment was made of the residual fertility in the plots of the non-clover treatments, both as grass and when ploughed and cropped with oats. Clover dominance was established in the clover treatments by the end of 1950. In view of the practical importance of the influence of fertilizer nitrogen on clover-dominant swards a subsidiary experiment to study this was started on these swards in 1951 and continued in 1952 and 1953. EXPERIMENTALThe experiment was carried out on a level field of light loam which had been under arable crop for 3 years. A soil analysis made during May 1948, gave the following results: available P 2 O 5 , 8 mg./ 100 g.; available K 2 O, 9 mg./lOO g.; loss on ignition 11 %; pH 5-9. After this soil analysis, ground limestone (48% CaO) was applied at the rate of 1 ton per acre and the land was ploughed. A further 1 ton per acre of ground limestone was applied before the land was ploughed again in early summer; basi...

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Soil Fertility and Pasture Growth

Cited by 22 publications

References 0 publications

Pasture management trials on unploughable hill country at te Awa

Pasture management trials on unploughable hill country at te Awa

The effect of nitrogenous fertilizers on white clover

The intensive production of herbage for crop-drying Part VI. A study of the effect of intensive nitrogen fertilizer treatment on species and strains of grass, grown alone and with white clover

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