LIME RESPONSES ON GRASSLAND

New Zealand Journal of Agriculture, Volume 64, Issue 4, 15 April 1942, Page 231

LIME RESPONSES ON GRASSLAND

The investigation described in this article deals with the response which may be expected from the umiimiiiiii' application of ground limestone to pastures in the main farming districts of the Dominion. This work has been carried out over the past 15 years

by means of over 1,400 small-scale observational E trials which have been laid down throughout the | length and breadth of both Islands. The results from these plots have been checked against accurate pasture-mowing trials.

- By -

A. G. ELLIOTT,

Crop Experimentalist, and

P. B. LYNCH,

Assistant Crop

Experimentalist, Fields Division.

THE problem of assessing the response of New Zealand’s grassland to lime could be met only by a largescale investigation, and 1 ' to this . end the “response survey” method of usinglarge numbers of small-scale trials has proved .an outstanding success. There is no doubt that the problem has merited such attention, because a large proportion of the soils of the Dominion are deficient in lime. Moreover, at the present time, when we are forced back on our own resources, the maximum and most efficient utilisation of our output of ground limestone assumes even greater importance than formerly.

The survey will be confined to the use on pasture of ground limestone (carbonate of lime) as distinct from burnt or slaked lime. Although, of course, the latter forms will give at least as efficient results as the. carbonate, their use is on a restricted scale due to the variation in composition of the product, the unpleasantness of the material to handle, particularly in the case of burnt lime, and the higher price. Where cartage costs are heavy, however, in certain, circumstances it may be advantageous 5 to use burnt lime, as it is -more concentrated than the carbonate, and 11 or 12 cwt. of . a good product should give equivalent results to 20 cwt of ground limestone. Articles by the authors in previous issues of the “Journal of Agriculture” of Februay and June, 1941, have examined the value of ground limestone

in respect' of its fineness of grinding and hardness of rock, and also have analysed the problem of the most effective method of applying lime. In the former case it was found that the average commercial limestone was a perfectly satisfactory product provided its purity was sufficiently high and that it was ground sufficiently finely to enable 50 per cent, of the material to pass through a sieve with 30 meshes to the inch. In the latter instance an application of 1 ton of lime every four years was recommended for the Marton soils, which have ,a fairly high lime requirement. In the trials to be examined, good samples of commercial limestone were used, and these were applied at the rate of 1 ton per acre as an initial dressing when the trial was laid down and. 5 cwt. per acre as an annual dressing subsequently.

Layout of Trials

Although these trials vary according to. the comparisons being made, the standard “L.P.K.” lay-out which has been used in the majority of cases involves the crossing with lime of four plots— (1) No manure; (2) superphosphate; (3) superphosphate plus potash; and (4) potashto give eight treatments in all,- namely, the four treatments as given both with and without lime. The response to lime has been measured as the difference in the response of superphosphate plus lime from that of superphosphate alone or, where a marked potash response has been, observed, the -difference taken has been of superphosphate plus potash plus lime, between superphosphate plus potash. The effect of possible deficiencies of phosphates or potash is overcome by such comparisons.

Trials are observed four times in each year, and are laid down for a minimum of three years. Each plot is compared in turn with the “no manure” strip which surrounds the plots, and each trial is laid down in duplicate in the same field. This gives many comparisons, the agreement between which is important in assessing the reliability of the trial. Many factors operate to confuse the observer, who has to be trained not only to recognise sward differences, but also to

examine such differences in the light of other features, such as the type of sward, the system of farm management, the effect of stocking, the time of making observations, the uniformity of soil and pasture, and the history of the trial area, and he has to avoid carefully any personal bias. Large numbers of trials are required not only to ensure a coverage of all districts, but also to give sufficient results so that the effect of the foregoing sources of variation may be examined and eliminated. A system of numerical “points” is adopted, by means of which the observer allocates a figure to each treatment according to the degree of response shown by the plot. The points so allocated are later summarised and used in making the treatment comparisons.

Mowing Trials

Mowing trials are replicated trials, usually carried out under the “mowing and grazing technique” devised by Hudson, and these have been laid down at Ruakura and at Marton. In all cases, agreement was secured between these trials and the observational trials. Briefly, the mowing trials have indicated three/ main features concerning the response of pastures to lime, namely: — 1. The greatest response occurs in the summer and autumn period when clover production is greatest, due probably to the marked stimulation of clover . growth by lime. 2. The response to heavy lime applications is usually greatest in the second year. after application, but is generally marked for four or five years or even longer. 3. An increase in production of from 20 per cent, to 25 per cent, can usually be observed as “slight” and one of from 40 per cent, to 50 per cent, as “marked.” However, this very largely depends on the type of sward, the species responding, and the time of the year, and is based merely on personal opinion derived from numerous observations made before cutting the plots for weighing.

Lime Responses In Different Districts

The maps which accompany this article should be examined in conjunction with the . following survey. Each circle on the map represents an observational. trial, and the lime response observed on that trial is indicated as described. The result. is a picture of the responses throughout the Dominion. It will be noted that there is a definite grouping of certain

types of response into districts, and here is seen the value of the survey, Eventually, it is hoped to relate these responses to the soil by means o f the soil survey maps, and when this work is completed it will be posible to define accurately the areas on which lime is required, and also probably to give more exact recommendations regarding the amounts of limestone and other fertilisers, to' apply, The present survey is preliminary in the sense that this section of the in-

vestigation has been completed only in one or two districts. Where the responses as shown by the trials have been examined in the light of probable soil requirements as indicated by the soil survey, very satisfactory agreement has in most cases been reached, Additional work which it is hoped to complete eventually involves the analysis of the herbage to examine the uptake of nutrients by the plants in relation to the type of soil and the type of treatment applied.

NORTH ISLAND

(a) North Auckland In general, this district shows marked responses to lime. The area is a patchwork of different soils, however, and while the gumland soils, brown clays, and . ironstone soils respond extremely well to lime, some of the alluvial flats, as at Dargaville, and the sandy coastal soils, show little effect from such treatment (see the “Journal” for March, 1940). The proportion of soils not requiring lime is low. Considering the district total o'f 102 trials, 50 show good lime responses, 35 show slight lime responses, and 17 show no effect from —that is, a lime response was obtained in 83 per cent, of the trials. (b) Central Auckland Many of the soil types found in this district are also common further north, and consequently the manurial : responses are similar to those in North Auckland. There are large areas of

red-brown volcanic soils which respond to lime, and, in general, heavy applications of limestone should be made on all soils except possibly on the fertile river flats and coastal sands. Out of 40 trials, 15 show good lime responses, 10 show slight lime responses, and 15 show no response to limethat is, 62.5 per cent, of the trials indicate the need for liming. (c) Waikato This district is fortunate in that a detailed soil survey of a typical section the Waipa County— followed by a comprehensive manurial research programme involving both mowing and observational trials. Consequently, the district can now be accurately divided . into areas according to their fertiliser requirements (see the “Journal” for January, 1940). The soils of the district include peats and peaty soils and volcanic loams and clay loams which show variations according to the ash shower from which they are derived. Lime responses have been obtained on all of these soils, but the

dressing required is not as heavy as that needed further north, particularly on the lighter soils. - An application of from 10 cwt to 20 cwt of ground limestone every three to four years should be adequate. In 64 trials, 1 shows a good lime response, 46 show slight responses, and 17 no responses to lime, so that 73 per cent, of the trials have indicated some degree of lime requirement. (d) Thames and Coromandel Ten trials on the fertile marine silts of the Hauraki Plains have shown no responses to lime or fertilisers. On the hill soils of the Coromandel peninsular there is probably a greater need for lime, as one trial shows a good response, one a slight response, and one no response to lime. Further work is needed in this area before definite recommendations can be made. (e) Bay of Plenty Soils include leached pumice sandy loams (as at Waihi), free pumice sandy

loams of the hill country, free coastal soils also derived from pumice, free sandy pumice soils, and peaty loams. (See the “Journal” for December, 1941.) In practically all cases lime responses are small or absent. Nevertheless, light applications of limestone should not be discouraged, particularly in the older settled localities. Out of 104 trials, one showed good responses, 17 slight, and 86 no responses to lime, making only 17 per cent, of the trials indicative of a lime deficiency.

(f) Rotorua

This district largely comprises soils derived from . recent pumice, and one would not expect such land to be limedemanding. Out of 22 trials, only 6 show a slight lime response (27 per cent.), and these experiments -are mainly located on the borders of the district where the pumice soils intermix with other types.

(g) Te Kuiti-

Taumarunui

As one approaches the high-rainfall hill country of these districts, the lime response increases. The soils are subjected to considerable leaching, and are older than the pumice . soils with which we have been dealing. The limestone country and the alluvial flats do not .require lime to the extent of the clay loams of the hills. Altogether; 38 trials were laid down in this area, and 5 showed good lime responses, 23 slight, and 10 no responses to lime; thus, 74 per cent, gave positive results for lime.

(h) Taranaki

The soils of Taranaki are mainlyderived from various ash showers of Mount Egmont,' and differ from one another according to the nature of the original volcanic material. . Although they are in a district of heavy rainfall, the soils are “young” and lime responses are correspondingly small* or non-existent, .except possibly in the

country around Stratford, which is of comparatively high altitude. In Taranaki, out of a total of 79 trials, 4 gave good, 18 slight, and 57 no ' responses to lime, making 28 per cent.

of the experiments indicative' of the need for liming. (i) Wanganui-Taihape-Ohakune Except for the coastal region, this area receives a heavy rainfall, the altitude is considerable, and the majority of the soils are fairly mature and have been subjected to much leaching. Near Ohakune the soils are of a volcanic nature, and are very deficient in lime, a good response being obtained from lime in 10 out of 13 trials, and all 13 showing responses to the treatment. In the district as a whole, 22 trials out of a total of 52 gave a good lime response, 19 a slight response, and 11 no response to lime. Thus, 79 per cent.

of the trials showed good results from liming in marked contrast, to the neighbouring districts on both sides.

(j) ManawatuRangitikei

This district can be considered in two sections. The fertile Manawatu and Kairanga Plains show little or no responses to lime or fertilisers, but in the terrace country and on the Rangitikei Plains, such as in the Marton district, slight to fair responses to lime are obtained. At the Marton Experimental Area a 10 per cent, to 15 per cent, increase is usually obtained from the use of lime, but, as mentioned earlier, the response may greatly exceed this in the summer and autumn months. In the whole district there has been a total of 31 trials, and of these, 2 have shown good, 5 slight, and 24 no responses . to lime, so that 23 per cent, of the trials gave a lime response. . However, the majority of the trials not responding to lime . were located on the alluvial plains.

(k) Woodville-Dannevirke

This part of southern Hawke’s Bay has been considered separately, as it is a dairying district of high rainfall in contrast to the lower rainfall, sheep country of the rest of the Province. Lime responses are not marked because much of the country is of a fertile alluvial nature. Out of 25 trials, 10 show slight and 15 no responses to lime, 40 per' cent, being indicative of a slight lime deficiency.

(I) Levin-Paekakariki

On the fertile Horowhenua Plains and the low altitude country of the coastal region generally, little lime responses are obtained either on the sand country or on the alluvial plains. The foothill country is, however, rather deficient in lime, as, in greater degree, are the hills between Wellington and Paekakariki. The district has had a total of 23 trials, 2 showing a good, 6 a slight, and 15 no lime response, but the percentage of trials showing the need for lime (35 per cent.) covers, as indicated, two types of country with different lime demands.

(m) Poverty Bay-Hawke’s Bay- W air arap a

The east coast sheep country of the North Island embraces very many soil types, as has been indicated in the soil survey of Hawke’s Bay. Briefly, however, we may consider some of them as follows. The fertile

alluvial plains of Gisborne and Hastings show little or no response to lime or fertilisers. The limestone hill country which makes the best of the sheep districts, apart from the plains, in Hawke’s Bay and the Wairarapa is not greatly in need of lime, nor are the pumice derivative soils to the north of Napier. Lime responses tend to be more marked in the foothill country, such as at Puketitiri to the west of Napier and in parts of the Wairarapa Plains. In other scattered localities, mainly in areas where the rainfall is heavier than the average and where the soils are more “mature,” increased returns follow the use of lime. In the district as a whole, good lime responses have been observed on four out of 126 trials, slight responses on 34, and no effect from lime has been found on 88 trials. Thus, 30 per cent, of the experiments have indicated a lime deficiency.

SOUTH ISLAND

(a) Nelson

Soils of the Nelson district form three main types. These are the alluvial plains, which show little or no responses to lime, the clay loams of the eastern foothills and the clays of the Moutere Hills, both of which latter groups give marked responses to lime. It is therefore difficult to give a figure relating to the district as a whole, and most of the trials have been located on the intensively farmed flat country, where the detection of responses is difficult. Out of a total of 30 trials, 5 give good, 7 slight, and 18 no responses to lime. Thus, 40 per cent, of the experiments show the need for lime.

(b) Westland

Including the Murchison district this area, subjected as it is to veryheavy rainfall, has suffered severe leaching. Thus, marked lime responses are to be found throughout the whole district. Good responses were observed

on 50 out of 77 trials, slight responses on 22, and only 5 showed no effect from lime, giving 94 per cent, of lime responsive experiments.

(c) Marlborough The Marlborough Province may be considered in three sectionsthe higher country of the Sounds district, which gives good lime responses, the alluvial plains of the Wairau Valley and at Seddon, where responses are smaller but still definite, and the heavier rainfall country to the south showing more marked results from lime. Out of 48 trials, 8 have shown good, 36 slight, and 4 no responses to lime, and 92 per cent, of the experiments show that increased returns follow the use of this material.

(d) North Canterbury

The district surveyed is that centred round Hawarden. The soils on

both the hills and the valleys are limedeficient, as is indicated by the fact that 23 trials out of 44 showed good, 16 slight, and only 5 no responses to lime. The percentage of trials giving lime responses was 89 per cent. (e) Akaroa The Akaroa Peninsula, although it carries many different soil types, is almost entirely lime-deficient country, as is shown by the fact that 14 trials show good lime responses and-7 slight, whereas no responses have been found on only 4 out of the total of 25 trials. The percentage of trials giving lime responses is 84 per cent. (f) Canterbury Plains and Foothills Trials have indicated marked responses- to lime on practically the whole of this area, and some outstanding instances of the effect of liming on the Plains have been given in previous issues of the “Journal,” the. most recent being that of February, 1941 ' (page 99). Some of the very recent, heavier alluvial country along the banks of the rivers and near Christchurch may- not be as responsive as

the remainder of the Province, and there appears to be a small area near St. Andrews where less effect is obtained from lime. Nevertheless, by far the greatest area of the ' district responds very markedly to this dressing. Out of a total of 231 trials, 121 gave good, 70 slight, and 40 no lime responses, 83 per cent, showing the need for lime. * (g) North Otago In marked contrast to the districts north and south, liming has given only small responses on much of the Oamaru country. Particularly, as would be expected, is this the case on the limestone hills and the river flats derived from this material. Good lime responses were seen on only 1 out of 21 trials, slight, responses on 3 and none on 17, indicating that v in but 19 per cent, of the experiments has the effect of lime been observed. (h) Central Otago - . This is a district - where little or no - effect has been seen from -the use of fertilisers.’ or lime. . The soil types vary, from the most fertile schists to the - most barren deteriorated and

eroded country, but the factor operating to prevent the responses showing is the lack of water. On irrigated land the effect of water is so striking that the response from fertilisers and lime is negligible in comparison, while where water is not applied, growth over the greater part of the year is so small as to be insufficient to show the effect of top-dressing. Of 48 trials laid down, 2 showed a good response, 13 a slight, and 33 no response to lime. Thus, only 31 per cent, of the experiments have shown any effect from liming. (i) Dunedin-Balclutha The majority of soils in this area are deficient in lime, good responses being observed on all farming land apart from the most fertile river flats. Out of 56 trials, T 7 show marked, 22 slight, and 17 no lime responses, and 70 per cent, have been indicative of the need for liming. (j) Southland This area has long been the greatest user of lime, and trials have shown that there is every reason to apply the usual heavy lime dressings

On most of the country. The experiments not showing marked lime responses are, in the majority of cases, located on land which has been heavily limed in the past,' because it is difficult to find well-managed farms which have not been so treated. Fur-

ther, the effect of such heavy liming lasts over a long period, sometimes up to ten years, so that many trials may unknowingly have been influenced by such dressings, and the percentage of trials67' per cent,responding to lime is therefore 'an • under-estimation of

the position. Of 106 trials, 33 have shown good, 38 slight, and 35 no responses to lime.

Summary

The accompanying table summarises the position with regard to liming in New Zealand. Districts where the heavy liming of pasture, should be a standard practice — assuming that the area is sufficiently accessible and of relatively easy topographyare North and Central Auckland, Waikato, Te Kuiti-Taumarunui, Wanganui-Ohakune, parts of the Woodville and Levin-Paekakariki districts, the heavy land of Nelson, and practically all farming land in the rest of the South Island except in North and Central Otago.

Acknowledgments

.A survey of this nature depends wholly on the interest and skill of field officers, and the Instructors of the Fields Division have proved more- than equal to the task. Thanks are also due to the officers of the Soil Survey Division, Department of Scientific and Industrial Research, for their helpful co-operation, and to the hundreds of farmers on whose farms the trials have been carried out and who have always been willing to assist in their management.

District. Total Number of Trials. Trials Showing: . ■ Percentage of Trials showing . Lime ' Responses. Good Lime Responses. ' Slight ” Lime Responses. No Lime. Responses. North Auckland 102 50 35 17 83 x Central Auckland 40 15 10 15 62.5 Waikato ... .. 64 1 46 17 73 Thames-Coromandel .. 13 . 1 1 11 15 Bay of Plenty .. 104 1 17 86 17 Rotorua 22 — 6 16 27 Te Kuiti-Taumarunui , 38 5 23 . 10 74 Taranaki 79 4 18 57 28 Wanganui-Ohakune .. 52 22 19 11 79 Manawatu-Rangitikei 31 2 5 24 23 Woodville-Dannevirke 25 — 10 15 40-Levin-Paekakariki 23 2 6 15 35 E. Coast—Nth. Island 126 4 34 88 30 North Island 719 107 . 230 382 47 . Nelson .. .. 30 . 5 7 18 40 Westland 77 50 22 5 94 Marlborough A 48 8 : 36 4 92 North Canterbury 44 23 16 5 89 Akaroa .. .. 25 14 7 4 84 Canterbury .. 231 121 70 40 83 North Otago '.. 21 1 3 17 19 Central Otago . . 48 2 13 33 31 Dunedin-Balclutha 56 17 22 17 70 Southland .. 106 , 33 38 35 67 South Island • 686 274 234 178 74 •