LIMING AND MANURIAL TRIALS WITH RAPE AT MARTINBOROUGH.

New Zealand Journal of Agriculture, Volume XXVI, Issue 2, 20 February 1923, Page 108

LIMING AND MANURIAL TRIALS WITH RAPE AT MARTINBOROUGH.

SECOND YEAR'S RESULTS.

F. W. GREENWOOD,

B.A., Instructor in Agriculture, Wellington.

In the Journal for April last an' account was published of liming and manurial experiments with rape, which were being conducted ' at Martinborough, in the Wairarapa district. The results of the first season’s trials may be summarized briefly as follows : (i.) The local Martinborough lime on unmanured plots gave results 83 per cent, higher than those from plots which were neither limed nor manured. (2.) The average of all plots unmanured but limed was 75 per cent, higher than that of plots neither limed nor manured. (3.) The use of Mauriceville lime without manure . increased the yield by 100 per cent.that is, it doubled the return obtained from unlimed plots without manure. (4.) Ephos phosphate used with lime gave results 9-3 per cent, higher than those from Ephos without lime.. Allowing 7 per cent, for margin of error, this still indicates that Ephos with lime, in the wet spring of last season, was, if anything, slightly more efficacious than .Ephos alone. (5.) Gear superphosphate (which contains, a small percentage of nitrogen in addition to water-soluble phosphate) gave 19-4 per cent, better results with lime than when used alone ; or, again allowing 7 per cent, ' for' experimental error, an increase of 12-4 per cent. (6.) Nauru. ground-rock phosphate, used alone, showed results neither better - nor worse. than when used with lime. (7.) All limed and manured plots gave results from 90 to 100 per cent, better than those from plots untreated either with lime or manure. Among .the manurial plots themselves there - was little or no difference. The experiment was continued this year with slight modifications in the manurial treatment. The limed plots remained as before, and no further lime was applied this year. . The manurial trial plots, each 1 acre in area, were as follows : (1) Control (no manure) ; (2) 1 cwt. Nauru ground-rock phosphate with 1 cwt. Nauru superphosphate per acre (in lieu of Ephos used last season).; (3 and-4) . two consecutive acre plots, each treated with 2 cwt. Nauru ground rock per acre; (5 and 6) two consecutive plots, each treated with 2 cwt. Nauru superphosphate per acre (7) 2 cwt. Gear rape-manure per acre. This season rape and grass were sown in combination, the ultimate object of the experiment being to test the effect of liming and manuring on the establishment of ordinary permanent pasture on this class , of soil. Towards the middle of December the. rape crop, chiefly owing to the dry weather, showed signs of going off. Weighings were therefore taken on 18th and 19th December, so as to allow of the- lambs being turned into the paddock. . The weather record for Martinborough ; shows that the months of October, November, and December, . 1922, -were comparatively dry. The rainfall and number of wet days for these months were: October, 0-98 in., 8 days; November, i'2oin., 11 days; December, 22 in.,. 10 days. The total rainfall in 1922 was 24-53 in., with 157 wet days.

The results from the 49 plots comprised in this season's experiment, expressed in tons of rape per acre, are shown in the following table : —

On the control plot, where no manorial treatment was employed, the average yield from unlimed .’plots was 3-96 tons, while that, from limed plots was 5-79 tonsa difference of 1-83 tons, or 46 per cent., as compared with one of 75 per cent, last year. The average yield from plots treated with Martinborough lime was 5-14 tons, and that from those with Mauriceville lime 5-95 tonsa difference of 0-84 tons, or 16 per cent., as against one of 17 per. cent, last year. . It will therefore be seen that for the . last two seasons the difference in the effects of the uncrushed Martinborough lime and the crushed Mauriceville product has been both slight and constant. . In the manured plots I cwt. Nauru ground rock mixed with 1 cwt. Nauru superphosphate on unlimed plots gave an average yield of 6-96 tons, while on limed plots the average was 9-77 tons, a difference of 2-81 tons, or 40 per cent. On the two i-acre plots treated with Nauru ground rock the average yield for the limed portions was 9-06 tons, and for the unlimed 6-75 tons, a difference of 2-31 tons, or 34 per cent. Last season, as we have seen, no such difference showed itself, but as the soil in the whole paddock is sour, and has a somewhat impermeable subsoil consisting of an ironstone . pan at a depth of 12 in. to . 18 in., some such result might be expected, though hardly in so- pronounced a fashion. However,- the great benefit derived from lime is evident throughout the experiment. Superphosphate with lime. gave 241 tons per acre, or 33I per cent, more than when used alone. The margin here is much wider than that shown last year. An increase of onethird in the weight of a crop should serve as an irrefutable argument in favour of the use of superphosphate after lime, rather than alone, on such soil in the Martinborough district. Where Gear rape-manure was used with lime the yield was at the rate of 7-76 tons per acre, while the manure used alone yielded at the rate of 6-96 tons, a difference of o-8 tons,. or 10 per cent. This still leaves a margin of 3 per cent, if 7 per cent, is allowed for experimental error. There is therefore here, as on the other manured plots, a slight indication in. favour of the use of lime.

Comparing the manurial plots apart from liming considerations, both in actual and percentage yields (the control plot being represented by 100), the following results are obtained : Control (no manure), 4-88 tons per acre (100) Nauru ground rock with Nauru superphosphate, 8-37 tons (172); Nauru ground rock, 7-91 tons (162) Nauru superphosphate, 8-44 tons (173); Gear rape-manure, 7-36 tons (151).

Manure. s a Control Tons 3 Lime). MartinTons 3 borough Martin- Lime. borough Tons Lime. Mauricevill Tons Lime. Mauricevill Control Lime. Lime) j Control 3 3 S’ S' Lime) Hjjoa \ Tons Ton Martin- Mauricevill borough Lime, Lime. Control Ton 1 Lime) (no Mauricevill Lime. Control (no Lime) Control .. .. ... 3-21 4-50 5-46 4-17 5-78 6-42 4-50 Nauru rock and super . . 6-42 10-92 .11-25 ' 7-71 9-64 9-64 6-75 Nauru rock ... 6-io 10-28 10-92 6-42 • 7-71 8-03 7-07 Nauru rock . . 6-42 9-64 io-6o 8-03 9-00 9-00 6-42 Super .'. . . . . 6-42 10-92 11-25 7-7 1 9-64 9-64 L 6-75 Super............ , ... 7'7° io-6o io-6o 8-35 9-32 , 9-64 .. ' 7-07 Gear rape . . 7-71 8-67 9-00 6-42 ; 6-75 7-32 6-75