EARLY-POTATO GROWING IN FRANKLIN COUNTY.

New Zealand Journal of Agriculture, Volume XL, Issue 4, 22 April 1930, Page 232

EARLY -POTATO GROWING IN FRANKLIN COUNTY.

MANURIAL EXPERIMENTS AT PUKEKOHE, 1926 TO 1929.

J. E. Bell,

Instructor in Agriculture, Fields Division, Auckland

Notes on the Industry.

PoTATO-growing is an important farming industry in Franklin County, and is carried out on the basic volcanic soil areas which form the northern boundary of the Lower Waikato Basin. The country consists of low rolling downs, rising occasionally into flat-topped volcanic cones, and was originally covered in heavy bush. The soil is extremely suitable for early-potato growing, being light in texture, dark red in colour, and naturally fertile. The volcanic area lies fairly near the sea, and does not suffer severely from frosts. On the elevated volcanic cones frosts seldom occur and are never severe. The mean annual rainfall is about 50 in., and is well distributed. January and February are usually the driest months, and July and August the wettest.

Farms producing potatoes fall roughly into two classes namely, “ truck ” farms of about 10 acres, which produce early potatoes, onions, and other vegetables, and dairy-farms on which potato-growing is a side line. The farms which produce the earliest potatoes are situated on the flat-topped volcanic cones, the chief of which is.Pukekohe Hill, where the winter frosts are not severe and early potatoes can- be safely planted in winter. The earliest crops are planted from the middle of May to the end of June. On the lower volcanic areas, where the crops cannot be planted with safety before July owing to winter frosts, the growing of second-early potatoes is combined with dairying. Naturally the dairy - farms are larger than the truck farms, and range roughly from 30 to 100 acres and over in area.

Crop-rotation and Cultivation.

On the small truck farms which grow the earliest potatoes the land is usually kept under cultivation for three or four years, and then sown in pasture for a year or two before being again broken up for another course of cropping. Potatoes are usually the first crop taken after grass, and the land is skim ploughed in the autumn, disked, and then deep ploughed and worked up to a fine tilth with disks and harrows ready for planting in May or June. The early-potato crop is dug in September-October, and is followed by a second crop which is planted in November-December and dug in March-April. Two crops a year may be thus grown for three or more years in succession. The rotation, however, is frequently varied by growing onions, carrots, or cabbages in place of potatoes. Catch-crops of barley, lupins, or white mustard for green-manuring are often grown after the second crop.

On the dairy-farms potatoes are grown in rotation with grass supplementary annual crops, such as mangels and soft turnips. The potatoes are planted in July-August and dug in November-December. Mangels and soft turnips usually follow the potatoes, the mangels being sown early in specially prepared beds and transplanted after the potatoes are dug. The inclusion of potatoes in the cropping rotation on dairy-farms provides a valuable cash crop, which helps materially to reduce the cost of production of roots and green crops grown for the supplementary feeding of dairy cows.

For early crops, with which the haulms do not grow to a normal size, the potato sets . are planted in. to 12 in. apart in 27-in. rows. For the later-sown crops the sets are planted 12 in. to 15 in. apart in 33-in. rows. On truck farms the sets are usually hand - planted in furrows after the single-furrow plough, but the ridge plough is also used to some extent for planting.. The fertilizer mixture is broadcast by

hand along with the sets. On dairy-farms and on level areas mechanical planters and diggers are often used in place of hand labour. As soon as the crop is up it is hand-hoed, and when the rows can be distinctly seen horse-hoed, followed later by another horse-hoeing and finally a moulding.

Varieties and Seed

Northern Star (Gamekeeper) is about the only variety grown. It withstands late blight fairly well, and suits the double-cropping system. Many attempts have been made in the past and are at present being made to replace Northern Star by other varieties, but no other variety has yet been established as a serious rival. Before the incidence of late blight other varieties, such as Up-to-date, were grown at. Pukekohe, but are now found to be unsuitable. Any variety to succeed there must be resistant to late blight and be suitable for double cropping.

Large cut seed, which provides a reserve of plant-feed and gives the young plant a good start, is used for planting the early crop. From this crop small tubers are usually selected for seed for the second crop. These are greened in the sun, and the stem end cut just before planting. Growers contend that cut seed begins growth earlier than uncut seed, and cut seed is almost universally used. The produce from the second crop planted with small seed is usually all sold, and the seed for the early crop is obtained by planting a special area of the second crop with large cut sets. This area is harvested early, and the large tubers are used for planting the following early crop. Some of the-seed picked from the second crop is not planted for the early crop, but is “ kept over ” and planted immediately after the early crop is dug in September and October, to be dug in January and February. The seed from this crop is not saved for further cropping, as its vitality is considered to be lowered by this practice.

Disease and its Control.

The potato-plant being subject to many diseases, it might be expected that the continuous growing of potatoes would result in grave deterioration of the lines used at Pukekohe. ’ The care taken by the growers with their seed, and the practice of digging the crop while the tubers are immature, are primarily responsible for the limited prevalence of virus and other diseases in the crops. There is very little disease evident in the first crop, but wilt diseases show up to a certain extent in the second crop. Epidemics of “ mattery eye ” have occurred in the past to such an extent that growers fear it more than any other disease. The practice of cutting the seed potatoes, enabling the growers to reject tubers with a discoloured vascular ring, has no doubt helped in reducing the incidence of wilt diseases. The humid climate is responsible for heavy yearly attacks of late blight, but this disease is usually kept in hand by spraying with bordeaux or burgundy mixtures. Spraying commences when the plants are 3 in. high, and is repeated at ten- or fourteen-day intervals, depending on the weather. Early blight sometimes makes an appearance, .but is of no importance. The potato-moth is fairly prevalent, and is encouraged by the quantity of potatoes left about in the fields every year. The grubs

may . cause a certain amount of damage to stored seed, and precautions have to be carried out to prevent the moths laying their eggs on tubers stored for seed from the second crop.

Harvesting and Disposal of Crop.

Prices for early potatoes are highest in the early spring, and in favourable localities growers endeavour, to produce crops which can be harvested as early in the spring as possible. The crops, however, cannot be harvested at too young a stage, since the produce will spoil in a few days and have a bad appearance when marketed. The crop can be harvested with safety when the tops are still green but have not reached their maximum growth, and some of the bottom leaves are just beginning to die. At this stage the eyes of the Northern Star (Gamekeeper) potato take on a pink tinge, and many growers judge the time for digging their crop by this sign.

The early crops on the hills are dug by gangs of Maoris, men and women, in charge of a responsible Maori man, who keeps a tally of the work of each digger and makes arrangements for the work and food. The grower usually supplies the food for the gangs while digging is in progress, and deducts the cost from the diggers’ wages. The diggers are paid from gd. to is. 6d. per bag, according to the crop and the market price of potatoes. The later crops on the lower flat land are sometimes dug with mechanical diggers, but hand digging is the usual practice.

The potatoes are picked up in two grades, and packed in bags, the full weight of which is 60 lb. Both grades are sold in the case of the very early crop, but later in the season, when the price of second grade falls to the price of seed size, they are kept by the grower for seed for further planting.

The early potatoes are sent all over the North Island, and as far south as Greymouth and Dunedin. The price received for early potatoes in September averages about £3O per ton; it drops rapidly as supplies increase, and by the end of October usually falls to about £lB. By the end of November the price has fallen to about £5 a ton and remains at this level till the winter.

Manurial Experiments at Pukekohe.

Summary of Experiments in 1926, 1927, and 1928.

In the early days of potato-growing at Pukekohe, soon after the land was cleared, no manuring was necessary, but after the virgin fertility was exhausted increasing quantities of fertilizers were used. At the present time 15 cwt. to 20 cwt. per acre of mixed fertilizers are used for the early crop, and 10 cwt. to 15 cwt. for the second. Until recently bonedust, dried blood, and nitrogenous guanos were the chief fertilizers used, but now increasing quantities of superphosphate and sulphate of ammonia are being used to replace the more expensive and less efficient bonedust and dried blood.

Experiments in the manuring of potatoes at Pukekohe were, started by the Department of Agriculture in 1926, and were continued in .1927, 1928, and 1929. Reports on the earlier experiments were published in this Journal for March, 1927, and June, 1928. . The object.. of these

experiments was to measure the usefulness of various phosph atic manures and to ascertain whether bonedust could be economically replaced by a cheaper phosphatic fertilizer. In the 1926 trials the fertilizers compared were 15 cwt. bonedust, a mixture of 7I cwt. superphosphate and 7I cwt. bonedust, and another mixture of 7| cwt. super and 7I cwt. Ephos phosphate, per acre. Bonedust contains about 4 per cent, of nitrogen, and sufficient sulphate of ammonia was added to the other phosphatic fertilizer mixtures used in the trial to make up their deficiency in nitrogen. In addition 2 cwt. sulphate of potash was added to each mixture. The results of this trial are given in Table 1, from which it may be seen that bonedust can be quite well replaced by super and Ephos, and that super is probably a more efficient phosphatic fertilizer than bonedust. ' However, it should be noted that the super and Ephos mixture contained its nitrogen in a water-soluble form, whereas the bonedust contained it in a sloweracting form, and later trials have shown that water-soluble nitrogen is very important in the manuring of the early potato crop.

(1) Plus 2 cwt. sulphate of potash. (2) Plus 2 cwt. sulphate of potash and if cwt. sulphate of ammonia. (3) Plus 2 cwt. sulphate of potash and 3I cwt. sulphate of ammonia.

In 1927. the trials were carried a stage further, and the manurial treatments used were 7| cwt. bonedust and 7| cwt. super, 7| cwt. Ephos and. 7I cwt. of super, and 15 cwt. of super, per acre. Sulphate of ammonia and potash were also added to the mixtures, as in the 1926 trials. The results of these trials are also given in Table T, and the relative yields were similar to those obtained in 1926. In 1928 these trials were repeated with additional treatments, in which Gafsa replaced Ephos in the mixture and Diammonphos replaced super and sulphate of ammonia. The Diammonphos treatment, when compared with the superphosphate mixture, increased the yield of table potatoes by 10 cwt. per acre. It contained nitrogen to the equivalent of i-6 cwt. sulphate of ammonia more than the super mixture, but the phosphate content was less by an amount equivalent to 3 cwt. super. These trials indicated that the early potato - crop responded best to water - soluble phosphatic and nitrogenous fertilizers, and that expensive bonedust could be economically replaced by them. . .

Experiments in 1929.

During 1929 three manurial experiments were carried out with early potatoes at Pukekohe. Experiments were laid down on the farms of Messrs. E. J. Campbell and G. T. Nicholson to determine the value of nitrogen and potash in addition to the basal phosphatic dressing of 15 cwt. super per acre. Another experiment was laid down on Mr. P. A. Miller’s farm to determine the effect of different degrees of concentration of manure in proximity to the . plant, and whether delaying a portion of the super dressing was beneficial. To ensure accuracy each treatment was replicated ten to sixteen times.

trial on e. j. Campbell’s farm

The experimental area on this farm was planted on 30th May, and the crop was dug and weighed on 21st October. The manurial treatments per acre were as follows : (1) Superphosphate 15 cwt. (2) Superphosphate 15 cwt., sulphate of potash 2 cwt., sulphate of ammonia 2 cwt. (3) Superphosphate 15 cwt., sulphate of potash 2 cwt., sulphate of ammonia 4 cwt. (4) Superphosphate 15 cwt., sulphate of potash 2 cwt., sulphate of ammonia 6 cwt. (5) Superphosphate 15 cwt., sulphate of potash 4 cwt., sulphate of ammonia 4 cwt.

Before digging the rows manured most heavily with sulphate of ammonia could be picked out quite easily, the tops being heavier and of a healthy green colour. The yields from the different treatments are given in Table 2, from which it can be seen that the addition of sulphate of ammonia to the basal phosphatic dressing has materially increased the yield. Comparing the yields from treatments 3 and sit is evident that increasing the sulphate of potash to 4 cwt. per acre has

decreased the yield below that resulting when only 2 cwt. of potash was used with the same amount of phosphates and nitrogen. The last column in the table gives the per-acre value for the increased yield over treatment I—the1 —the value of the extra manure, extra bags, and cost of digging and carting being deducted from the gross value of the additional table potatoes. The trial clearly indicates the value of sulphate of ammonia as a fertilizer for early potatoes. The high price obtained for early potatoes makes it possible to economically use fairly large quantities of this fertilizer, and in this trial the application of 6 cwt. per acre paid very well.

G. T. NICHOLSON’S FARM. This experiment was planted and manured on 29th May and dug on 25th October. The different treatments were as follows :

(1) Superphosphate 15 cwt. ' (2) Superphosphate 15 cwt., sulphate of potash 2 cwt. . ' (3) Superphosphate 15 cwt., sulphate of potash 2 cwt., sulphate of ammonia ■’ 4 cwt. . ' (4) . Superphosphate 15 cwt., sulphate of ammonia 4 cwt. (5) Superphosphate 4-6 cwt., sulphate of potash 2 cwt., Diammonphos 4 cwt. ■ As in the preceding trial the rows which had received nitrogen could be easily , picked out before digging. The yields obtained from the different treatments are given in Table 3. Treatments 1 and 2 do not differ significantly from one another; treatments 3,4, and 5 do not differ significantly from one another, but all are significantly better than treatments r and 2. Potash has had no beneficial effect on the yield. The value of sulphate of ammonia in increasing the yield is again demonstrated. Treatment 5 has the same quantity of phosphates, nitrogen, and potash as treatment 3, but part of the phosphate and all the nitrogen is in a different form ; there is no significant difference in the yield. . , . . .

P. A. miller’s FARM.

This third trial was set out to determine whether heavy applications of water-soluble fertilizers in direct contact with the potato sets had any deleterious effect on the initial establishment of the crop. The experimental area was planted on 10th June and dug on ist November. The crop was manured with a mixture of 15 cwt. superphosphate, 2 cwt. sulphate of potash, and 4 cwt. sulphate of ammonia, per acre, and the fertilizer was applied in the following ways: (1) In a narrow band 3 in. wide, with the potato sets ; (2) in a broad band 9 in. to 12 in. wide, with the sets ; (3) a mixture of 7 cwt. super, 2 cwt. sulphate of potash, and 4 cwt. sulphate of ammonia in a broad band 9 in. to 12 in. wide, with the sets, and the remaining 8 cwt. of super applied when the crop was up, on 14th September, as a top-dressing. The yields from the different treatments are shown in Table 4. No. 1 treatment is significantly superior to treatments 2 and 3, which do not differ significantly from one another. No bad effect on establishment of the sets was noticed for No. 1 treatment. Hence the close proximity of the manure to the potato sets was definitely advantageous in this trial.

Recommendations to Pukekohe Growers for Early Crops.

(1) Use a mixture of 12. cwt. to 15 cwt. superphosphate and 4 cwt. to 6 cwt. sulphate of ammonia, per acre, or (2) Use 4 cwt. to 6 cwt. Diammonphos per acre. (The respective prices of these fertilizers should determine which is to be used.) (3) The inclusion of about 2 cwt. potash per acre is an established practice in Franklin County. In the experiments conducted in 1929 potash was of no value in increasing yield, and there was no evidence to show that it conferred other benefits. However, further experimental evidence is required before the Department is prepared to advocate the exclusion of potash, the use of which for potatoes is normally regarded as a good practice. (4) Do not distribute the manure too widely in the rows ; the indications are that it is better to put it in a narrow strip a few inches in width along the row of sets. Note. — must be clearly understood that these recommendations may be subject to modification as further evidence is gained from experiments. The writer wishes to record his thanks to Messrs. Nicholson, Miller, and Campbell for their helpful co-operation in carrying out the 1929 manurial experiments.

* First-grade potatoes from this crop sold at £23 per ton.

* First-grade potatoes from this group sold at £2O per ton. t Decrease,

Year. Fertilizer. Yield of Table Potatoes. Tons cwt. lb. 1926 15 cwt. bonedust (1) .. .. .. Tons cwt. lb. 5 13 101 7I cwt. bonedust and 7J cwt. super (2) 6 6 90 7| cwt. Ephos phosphate and 7J cwt. super (3) 5 13 IO* ' 6 6 90 690 1927 7b cwt. bonedust and 7J cwt. super (2) . . 2 1 49 7| cwt. Epho.s and 7J cwt. super (3) .. 2 4 61 15 cwt. super (3) .. .. .. 2 1 49 2 4 61 2 5 80 1928 7| cwt. bonedust and 7I cwt. super (2) .. 3 i3 2 7J cwt. Ephos and 7J cwt. super (3) . . .. 3 13 67 15 cwt. super (3) .. .. .. . 3 15 22 4-4- cwt. Diammonphos (1) .. ■ ... 4 5 45 7| cwt. Gafsa phosphate and 7-J cwt. super (3) . 3 13 2 3 13 67 3 15 22 4 5 45 3 .14 6 7

Table 1. —Summary of Results for 1926, 1927, and 1928.

' Treatment. Yield per Acre. Increase of First-grade Potatoes over No. 1 Treatment. Net Value of Increase per Acre over No. 1 Treatment.* First Grade. Second Grade i jas'? ■ ■ ■ ■ ■■ ' ' Yield per Acre. Increase of First-grade Potatoes over No. 1 Treatment. Net Value of Increase per Acre over No. 1 Treatment.* First Grade. Second Grade v" ' Tons. Tons. Tons. ■£ s. d. (i) Super 15 cwt. ' Super 15 cwt. S’© 2 Tons. 3-02 0-79 Tons. 0’79 Tons. £ s. d. (2) Super 15 cwt., potash 2 cwt., Super 15 cwt., potash 3'91 0'79 0-89 14 0 0 • f ' ammonia 2 cwt. 2 cwt., 3-91 0'79 0-89 14 0 O (3) Super 15 cwt., potash 2 cwt., Super 15 cwt., potash ..4'65 . 0'74 1'63 27, 0 0 : . ammonia 4 cwt. • 2 cwt., 4-65 0'74 1-63 27 0 0 (4) Super 15 cwt., potash 2 cwt., Super 15 cwt., potash 5'ii o-8o . 2-09 35 0 0 ammonia 6 cwt. 2 cwt., 5-n o-8o 2-09 35 0 0 (5) Super 15 cwt., : potash 4 cwt., Super 15 cwt., potash ■ 4'3° 0-72 - - 1-28 ' 19 0 0 ammonia 4 cwt. 4 cwt., 4’30 0-72 1-28 19 0 0

Table 2. —Results in E. J. Campbell’s Trial.

Treatment. Yield per Acre. . Increase of First-grade , Potatoes over No. 1 Treatment. Net Value of Increase per Acre over No. 1 Treatment.* First Grade. Second Grade. Tons. Tons. Tons. £ S. d. (i) - Super 15 cwt. .-. Tons. 4-6 Ton's. ’ ' 0'52 Tons. £ s. d. (2) Super 15 cwt., potash 2 cwt. . . 4-38 . 0-54. ■ . O-22f (3) Super .15 cwt., potash 2 cwt., 5’32 0’51 0-72 800 ammonia 4 cwt. 5’32 0-51 0-72 8 0 0 (4) Super 15 cwt., ammonia 4 cwt. 5'32 . o-55 0-72 goo (5) Super 4-6 cwt., potash 2 cwt., 5-22 0’57 0-62 400 Diammonphos 4 cwt. 5’22 0-57 0-62 '4 0 0

Table 3. —Results in G. T. Nicholson’s Trial.

Treatment, Yield per Acre. First Grade. Second Grade. Tons. Tons. (i) Manure in narrow band with sets 5-27 0-66 (2) Manure in wide band with sets 4-5 0-63 (3) Part of manure in wide band with sets, and part 4'77 0-65 top-dressed later 4’77 0-65

Table 4. —Results in P. A. Miller’s Trial.