POTATO-MANURING EXPERIMENTS IN CANTERBURY, SEASON 1926-27.

New Zealand Journal of Agriculture, Volume XXXVII, Issue 5, 20 November 1928, Page 323

POTATO-MANURING EXPERIMENTS IN CANTERBURY, SEASON 1926-27.

METHODS OF APPLICATION OF FERTILIZERS

A. W. Hudson,

B.Ag., B.Sc., Crop Experimentalist, Fields Division

In continuation of the experiments on phosphate, potash, and nitrogen manuring of potatoes previously carried out (see Journal-, February, 1927), five further trials were made in the 1926-27 season. Two of these trials were largely concerned with methods of applying the fertilizers used.

The practice of sowing artificial fertilizers in the row with the seed potatoes (referred to herein as “ manure with seed ”) has of recent years been replaced largely by the drilling of the manures through every coulter of the manure-drill prior to sowing of the seed. This latter method will be referred to here as “ predrilling, and may be termed “ manuring of the ground as against “manuring the seed.” No reliable information on the relative merits of the two methods was available, so it was decided to test the point on two farms. Both experiments were conducted in the same way, except that in one case predrilling was done eight days and in the other twenty-three days before planting ; also, in the first case the potatoes were ploughed in and the manure with seed applied by hand, while in the latter case planting was done with a machine. The treatments used were as follows :— . (r) No manure. per Acre. (2) Superphosphate, 44/46 per cent, tricalcic phosphate 3 cwt. (3) Super 3 cwt., and sulphate of ammonia (20 per cent. nitrogen) .1 cwt., per acre . . . . • • ' 4 cwt. (4) Super 3 cwt., sulphate of ammonia 1 cwt., and sulphate of potash (48 per cent. K 2 O) 1 cwt., . per acre . . . . . . . . • • 5 cwt. METHOD OF EXPERIMENTS.

Predrilling of fertilizers was done in parallel strips, each | chain wide by 3' chains in length. Four strips of each of the treatments specified above were sown, hence there were sixteen parallel strips each | chain wide and 3 chains long. To ensure uniform cultivation the empty drill was run over the no-manure strips in the same way as on the manured ones.

Later the same manures were applied with the potatoes, which were planted in rows running across the sixteen |-chain-wide strips. Each plot was three rows in width and replicated six times. This resulted in sixteen different treatments, each of which occurred twenty-four times over the area. Fig. 1 illustrates the arrangement diagrammatically.

Digging was done by hand, the rows being marked off into |-chain lengths (corresponding to 'width of predrilled plots). Sorting into various grades was carried out with a potato-sorting machine.

Pet coot :, A . , poo SulpKoJoe. OF I. TREATMENTS. each i of Quantities in

Experiment 1 : On Farm of S. McIntosh, Kaiapoi.

Manures predrilled, 18th. and 19th October, 1926. .. Crop planted' 26th and 27th October. Potatoes ploughed in and manures with seed applied by hand. (Figs. 2 and 3). Variety:’ Dakota. .Previous history of field ; 1925-26, wheat ; 1924-25, potatoes, which followed a twelve to fifteen-year-old pasture.

OBSERVATIONS DURING PERIOD OF . GROWTH

In early December all rows having had manure with seed showed a stronger growth than the controls. The super plots were decidedly pale in colour as compared with those that received nitrogen, which were quite a deep green. At this time the predrilled manures did not show any visible effect on growth. . On 13th January the predrilled manures were, having an easily discernible effect on growth of tops (Fig. 4), and from this time onwards both methods of application of the fertilizers appeared to be equally effective as measured by appearance of the tops. The plots which received nitrogen were much # more healthy and vigorous in appearance than those having super alone. The latter still maintained a better growth than the no-manure plots.

The following table summarizes the results of the experiment: —

Notes,

i In estimating the monetary return from each treatment the following values per ton are assigned to the various grades : Table, /3 ; seed, ios. ; small, no value. From £4 to £4 10s. per ton is reckoned to be the local average of the past seven or eight seasons’ values of table potatoes for May delivery. Digging and cartage costs are about /i to £1 10s. per ton, according to the conditions of digging and distance of cartage to rail. . Hence £3 per ton seems a reasonable value to assign to table potatoes in the ground. Seed will vary in value from nothing to £J> or £7 per ton according to the demand, variety, and purity. From £2, 10s. to £4 is considered a fair average market value to give this class of potato, and, as the costs in digging and handling will be about the same as for tables, seed are valued at £x 10s. per ton in the ground. Since small (pig) potatoes are generally left on the ground they are here considered valueless.

The per ton charges enumerated will be practically the same whether the crop is one of 10 tons or one of 11 tons. On the other hand, per acre costs, such as ploughing, cultivating, moulding, &c., will vary per .ton, decreasing with increased yield and increasing with decreased yield. Such operations, however, cost the same per acre for manured as for unmanured crops.

Costs of manures : These have been calculated on the following approximate prices per ton : Superphosphate, £6 ; sulphate of ammonia, £22 ; sulphate of potash,

Profit resulting from use of manures : The amount in this column represents the value of the increase over no manure less the cost of the manure (for example, treatment 2, super, 3 cwt., with seed). Thus 7-24 tons table potatoes at £3 per ton are worth approximately £21 14s., and 2-73 tons seed at £1 10s. are worth £4 2s., a total value of £25 16s. ; deducting cost of 3 cwt. super at fp per ton, 18s., there remains a net amount of 18s. per acre. The value of the crop on the no-manure plots is £21 ns. per acre. Hence there is a £3 7s. greater return as a result of using 3 cwt. of super. . .

COMMENTS ON TABLE I

To facilitate comparison of the results of the various treatments Table 1 is divided into six parts, the principal considerations being embodied in the first three parts. The necessary comparisons in these parts have been examined statistically, and where significance occurs it will be indicated. The numbers in brackets given below indicate the number of treatment referred to (see Fig. 1).

Manures with Seed. — Super (2) has given a significantly higher yield of about tons of . table potatoes than no manure. The seed and small do not differ significantly in the two treatments. The difference in total yields is about i| tons in favour of the super.

Super -4- sulphate of ammonia (3) is significantly better than super (2) in all grades.

Treatment (4) containing potash does not differ significantly from treatment (3), and in any case it has not increased the monetary return.

Manure predrilled. — Super predrilled (5) is poorer in yield of table potatoes' and better in yields of seed and small than super with seed (2), although the totals do not differ significantly. The effect of difference in yields of the various grades has quite a marked influence on net profit as shown in the last column, treatment (2) giving 16s. per acre better return. This provides a very excellent example of the necessity of the determinations not only of total yield but of the yields of the different grades.

Super + sulphate of ammonia (9) and super + sulphate- of ammonia 4- sulphate of potash (13) have both yielded significantly lower in table, seed, and total than the corresponding treatments (3) and (4) applied with the seed.

Of the three treatments' predrilled it will be seen that any difference there may be is in favour of the super alone (5), and that both sulphate of ammonia and sulphate of potash have failed to increase the yield. In this experiment the method-of applying the manure with the .seed has proved the. better. ' ' .

Combination of Manures with Seed and Manures -predrilled. — None of these treatments is of sufficient merit to have caused additional profit from its use, and although the heaviest yields have resulted from treatments (11) and (15) the cost of the heavy dressings of manure has lessened the resultant profits.

The consistency with which the mixture of super and sulphate of ammonia with seed has proved a little better than the super alone, irrespective of what the predrilling treatment consisted of, can be seen

if treatments (3), (7), (11), and (15) are compared with (2), (6)., (10), and. (14) respectively. ’ . ■

Effect of Treatments on Percentages of various Grades. -The percentage yields of table potatoes throughout have proved to be very consistent, and range from 64-1 to 66-6, with the exception of the super with seed, treatment (2). In this case the yield of table potatoes was 68-9 per cent, of the total yield. It proved to be significantly higher than the no-manure plots, which gave 65-1. per cent, of tables. The super (2) gave a correspondingly and significantly lower percentage of seed and small kinds.. The super had 26-0 per cent, of seed and 5-1 per cent, of small, while all other treatments ranged from 27-1 to 29-0 per cent, of seed and from 5-8 to 7-1 per cent, of small.

Experiment 2 : On Farm of H. MeLenaghen, Killinehy.

Date manures. predrilled, 7th October, 1926. Crop planted with potato-planter on 30th October. Variety: Up-to-Date. Previous history of field : . Grass for several years.

OBSERVATIONS DURING GROWING-PERIOD.

From the time that the plants appeared above ground a marked superiority of the plots having manure with seed over no-manure plots was apparent. The predrilled manures showed no effect until some time after the crop was through, and on nth January, 1927, these plots appeared to be just as strongly grown as those having manure with seed. All plots having sulphate of ammonia and sulphate of ammonia + sulphate of potash were a much deeper colour than those having straight-out superphosphate. On nth January the plots were very similar in appearance to those on McIntosh's farm (Fig. 4). A complete summary of the results is given in Table 2 (next page).

COMMENTS ON TABLE 2. Manures with Seed. — The very considerable and significant increase in the yield of table potatoes of about i| tons as a result of using super with the seed (2) provides a handsome margin of profit to the extent of £4 per acre. ,

The addition of sulphate of ammonia to super (3), although increasing the yields of seed, small, and total yield to a significant extent, has failed when the financial side is considered. The yield of table potatoes in treatment (3) is lower than that of super (2), although not to a significant extent. A further comment on this is made below. The mixture containing potash (4) has in no way improved the yield over that of treatment (3) when potash is omitted.

The superiority of the treatments (2), (3), (4) applied with the seed over the corresponding treatments (5), (9), (13), which were predrilled, is very obvious. In every case, except in the comparisons between the seed and small on the two superphosphate treatments, the differences are significant.

Manures predrilled.— Treatments . (5), (9), (13) indicate that under this method of application both sulphate of ammonia and sulphate of potash have been instrumental in increasing the’yield. Since the increases are far from being profitable they have not been submitted to statistical examination.

Combinations of Manures with Seed and Manures f>r edrilled.— Like the experiment on McIntosh’s farm, some of the heavily manured plots have given the highest yields with, in the main, low monetary returns. The consistent effect of super -J- sulphate of ammonia applied with the seed in its relationship to super is again evident, although it has behaved somewhat differently than in previous experiments. Treatments (2), (6), (10), and (14), in which super has been applied with seed across all predrilling, are consistently higher in the yield of table potatoes and lower in seed, small, and total than (3), (7), (11), and 15 respectively, in which the nitrogen has been used. Hence the sulphate of ammonia, although increasing the total yield, has had the undesirable effect of reducing the yield of the more desirable table potatoes. Since the nitrogen has caused an increase in.weight of crop, accompanied by a reduction of the number of tubers- reaching -the large size, it is obvious .that there must, have been a considerable increase in the number of tubers actually formed, and. under more favourable conditions of growth a greater number of these could be expected to

attain a greater degree of size. The rainfall figures given below give a good idea of the type of growing-period experienced.

Potash used with the predrilled treatments shows a regular increase in table potatoes, although in the case of the mixture applied with the seed (4) it has been quite useless. • Each of the treatments (13), (14), (15), and (16) should be compared with that immediately above it. With the exception of treatment (14) none of the potash plots has given a better monetary return than the same treatment without potash.

Effect of .Treatment on Percentage of various Grades. — The no-manure plots had 497 per cent, of table potatoes and 43-6 and 67 per cent, of seed and small potatoes respectively. In every case where super alone was sown with the seed the percentage of table potatoes was highest and the percentage of other grades correspondingly low. Treatment (2) gave 56-1 per cent, of table, 38-2 per cent, seed, and 57 per cent, small; treatment (6) gave 56-5 per cent, of table, 37-6 per cent, seed, and 5-9 per cent, small; treatment (10) gave 56-4 per cent, of table, 37-7 per cent, seed, and 5-9 per cent, small; treatment (14) gave 58-7 per cent, of table, 36-2 per cent, seed, and 5-1 per cent, small.

AH the manured plots ranged from 51-3 to 55-6 per cent, of table potatoes, from 37-6 to 41-8 per cent, of seed, and from.6-4 to 7-4 per cent, of small. Hence all the manures increased the percentage of table potatoes and reduced the percentage of seed.

General Remarks.

The season under review was rather extraordinary in that the early summer was unusually wet and very favourable to growth, while the late summer was extremely dry. This is shown clearly by the following rainfall figures for Christchurch taken from the weather records published in the Journal: —

Rainfall Average Rainfall at 1926-27. same Station. Inches. Inches. October . . . . . . 2-84 i-68 November .. .. . . 3-98 1-87 December . . . . . . 3-55 2-06 January .. .. .. 0-62 ’ 2-21 ' February, . . . . . . o-8o 1-77 March .. .. . . 1-15 2-05

The dryness of the late summer caused crops to go off . early, consequently the tubers did not develop, and crops in general produced a large proportion of seed and small tubers. Under the prevailing conditions the method of applying manure in the row with the- seed gave much better results than predrilling. Whether this will be maintained in the future remains to be seen.

The effect of adding sulphate of ammonia to superphosphate was to increase the yield of all grades at McIntosh's (Kaiapoi), while at McLenaghen's (Killinchy) the increase has been in seed and small only, resulting, however, in a greater total weight per acre.

As in previous seasons, sulphate of potash failed to give results which warrant the recommendation of its use in Canterbury. '

(To be continued.)

No cwt. Super 3 cwt Super / cwt. of Solphaie. 3 cwt of A cwt. of No 1 No 5 . 5 (Pd) 9 N + S of/tmm. (Pd) 13 5+3 of A rnm. + 5 of Potasf (Pd} 9 0 k 'O * 5 .5 (Pd) • ! - 9 S + 5 oFAmm. (Pd) 13 3+3 of A mm. +, 3 of Potocsfx CPd) 0 k 5uupcr 3 cud I J 2 v5 (.W 3) 6 3 (Pct) 5 (WS) 10 J) +■ 5 of Amm. (Pd) 5 (W5) (Pd) 5 + 5 of A mm +5 of Potash 3 (W5) Super 3 cwt. cad. 3 Super 2 v5 ' (WS) 6 _ 3 (Pct) ■■ 3 . (WS) 10 ,3+3 of Amm. (Pd) 3 : (W S) 1 4 (PC^< } 3 + S of Amm +3 ofPotcLsri 3 (V5) ofPuJphcute. A . g 3 5 + 3 of A mm. (// 5) 7 3 + 5 cf Amm . (W3) 11 3 + 5 of Amm. tPd) 3 + 3 of A mm. (WSj 1 5 (Pd) 3 + S of A mm + 3 of Potash 3+S of A mm. (IV3) Amm. cwt. t g cwt >5tz/?ez' 3 3 + 3 of Amm. (W 5) 7 3+3 cP Amm. (WS) 11 3+5 (Pd) 3+3 ofAmm. (FAS} 15 • : (Pd) 5+5 of A mm + S of Potash. S + 5 ofAmm. (IdS.) $ Super of Sulphide. Amm. ! cwt. 3<+ZpAxtZe> of Sulphrdo of N 4 >5 + 3 ofAmm. + S of Pot. (IV 5) 8 S (Pd.) 3 +3 oPArnm. + 3 of Pot. (IVS) 1 2 3 + 3 ofAmm. (.Pd) 3 +5 of Pot.(W 3) 16 (Pd) 3 + S of Amm. +5 of Potash S + 3 ofAmm. + 5 of Potash (WS) H 33 fbep +1 4 . . J) +3 ofAmm. + 3 of Pot. (W 5) 8 , . 3 . (Pd) 5 +3 oFAmm. +.3 of Pot. (Id 5) 12 3 + 3 oFAmrz. (Pd) 3 +5 oFAmm.+S of Pot. (W 3) 16 ' ■ (Pd) 5 +3 of Amm. +5 of Potash. 3+3 oFAmm. + 5 oFPotash. (WS) 33 fdet. + Potash, / cwt.

Manures Predrilled (4 replications)

of Treatment. Treatment (see Fig. 1). Yield in Tons per Acre. Cost of ■ Manures per Acre. Profit from Use of Manure. Table. Seed. Small. Total. I No manure .. ... 5’88 2'59 0-56 9'03 Manures with Seed. 5’88 es wit s. 2’59 h. Seen d. 0-56 I. z 9-03 z s. s. d. d. £ s. d. 2 Super Super 7’24 2’73 o-54 10'51 0 18 0 3 7 0 3 Super -fc- sulph. of amm. 7-24. 2’73 o-54 10-51 0 18 0 3 7 0 3 Super -J- sulph. of amm. 7’51 3’25 o-68 n-44 2 0 0 3 17 0 4 Super + sulph. of amm. 4-7-69 3-22 0-69 n-6o 2 18 0 3 9 0 sulph. of pot.. Manures predrilled. 7’69 yes pre 3-22. drillec 0-69 I. n-6o ’ 2 18 0, 3 9 0 5 Super .. 6-8o 3-°7 0'74 io-6i 0 18 0 2 11 0 9 Super + sulph. of amm. ' 6-76 2-93 0-64 10-33 2 0 0 1 2 0 3 Super -j- sulph. of amm. -J-6-76 2-92 o-74 10-42 2 18 0 0 3 0 sulph. of pot. Super with Seed on Predrilled Manures 6-76 edrille named 2-92 •i Mat oelow. 0’74 wres 10-42 'lamed 2 18 below. 0 0 3 0 6 On super . . 7; 22 3-°9 0-69 11-00 1 16 0 2 19 0 IO On super 4- sulph. of amm. . . 7-64 3-n 0-72 u-47 2 18 0 3 2 0 *4 On super + sulph. of amm. 7'56 3’12 0-71. u-39 3 16 0 2 0 0 -f- sulph. of pot. 7-56 3’12 0-71 11-39 3 16 0 2 0 0 H Super-f Sulphate op Ammonia with Seed on Predrilled Manures named below. 7 . On super . . 734 3-3i o-77 11-42 2 18 0 2 10 10 0 0 11 On super + sulph. of amm. . . 7-78 3’42 0-76 11-96 4 0 0 2 18 0 15 On super 4- sulph. of. amm. 4- sulph. of pot. 7-82 3-4° 0-78 12-00 4 18 0 2 2 0 Super + Sulphate of Ammonia 4- Sulphate of Potash with Seed on Predrilled Manures named below. with Seed on Predrilled 8 On super . . .. 7-38 3’25 0-72 n-35 3 16 0 1 13 0 12 On super 4~ sulph. of amm. . . - 7’55 3-i5 o-66 11-36 4 18 0 0 18 0 16 On super 4- sulph. of amm. 7'57 3’32 0-71 1 i-6o 5 16 0 0 7 0 4- sulph. of pot. ■. 7’57 3’32 0-71 it-6o 5 16 0 0 7 0 ■ . •"

Table-1. —Results of Experiment on Farm of S. McIntosh, Kaiapoi.

of Treatment. Treatments (see Fig. 1). Yield in Tons per Acre. Profit from Use of Manure. Table. Seed. Small. Total. I No manure ■ . . . . .. 3-78 378 3’32 0’51 7-61 Manures with Seed. 3’32 0’51 7-61 £ s. d. 2 Super .. ... 5'29 3-61 °-53 9'43 4 0 0 3 Super -J- sulph; of amm. . . 5'16 4’°5 o-68 9-89 3 4 ' 0 4 Super -j- sulph. of amm. -J- sulph. 1 5-18 5-18 3’79 0-69 9-66 2 b 0 of pot. Manures predrilled. 3’79 0-69 9-66 2 0 0 5 Super .. . . . . . 4'3° 3-51 0-58 8-39 0 18 0 9 Super + sulph. of amm. . . 4-61 3’43 o-57 8-6i 0 13 0 43 Super + sulph. of amm. + sulph. 4-79 4'79 3\57 o-57 8-93 0 9 d of pot. Super with Seed on Predrilled Mani named below. 3’57 o-57 8-93 1 1 ires named below. 0 9 6 On super 5-41 60 o-55 9-56 3 10 0 IO On super -j- sulph. of amm. . . 5’55 3’71 o-59 9-85 2 19 0 14 On super 4- sulph. of amm. + sulph. 5’99 3’7° 0-52 10-21 3‘ 7 0 of pot. ■ . Super + Sulphate of Ammonia with Seed. . 5’99 mmonic 3-7° with 0-52 Seed. 10-21 3 7 0 7 On super ... 5-15 4-11 0-69 9'95 2 7 0 ii On super + sulph. of amm. 5-29 4-14 o-73 10-16 1 14 0 15 On super + sulph. of amm 4- sulph. 5’39 4-21 o-68 10-28 1 4 0 of pot. 5’39 4-2T 0'68 10-28 I 4 0 Suber + Sulphate of Ammonia + Sulphate of Potash .on Predrilled Manures named below. 8 On super ' ... 5-31 3’79 0-65 9'75 I 10 0 12 On super + sulph. of amm. 5'25 3'94 o-74 9’93 0 8 ' 0 16 On super + sulph. of amm. + sulph. 5’58 3’77 0-67 10-02 0 5 0 of pot. 5'58 3’77 0-67 10-02 0 5 0

Table 2.—Results of Experiment on Farm of H. McLenaghen, Killinchy.