STUDIES ON THE NUTRIENT STATUS OF SOME COCONUT SOILS IN CEYLON 2. THE "CINNAMON" SAND ON HORAKELLY ESTATE B. THE "HARD PAN" By D R . K . S A N D I R A S E G A R A M (Agrostologist, Coconut Research Institute of Ceylon) A N D D . E . F . F E R D I N A N D E Z (Senior Technical Assistant, Coconut Research Institute of Ceylon) 1. INTRODUCTION In an earlier publication (Paltridge and Santhirasegaram 1957) data from experiments with the "top-soil" were recorded. The present paper records experiments with the "Hard Pan" or clay layer occurring at a depth of approximately five feet. It was reported that plants growing in the "Cinnamon sand" would suffer from an acute deficiency of Potassium, of Calcium and of Nitrogen. They would also suffer from a deficiency of Sulphur, and from lesser deficiencies of Phosphorus and Magnesium. Leguminous plants would suffer from a deficiency of Boron and there was some evidence of an incipient deficiency of Copper. The present studies were undertaken to assess the nutrient status of the "Hard Pan" and to compare the results with that of the "top soil". In collecting samples of this soil an area where the "hard pan" was nearest the surface was selected and pits dug to expose the hard clay layer. Samples were taken from several such pits, and mixed thoroughly, after the coarser vegetable matter, such as roots were removed. That soil was then air dried in the laboratory and used to fill a number of 6 inch polysterene pots, each containing approximately 2,000 grammes of soil, air dry weight. The response to any nutrient was measured in terms of the dry weight of the plant grown in each pot. All pots were watered daily, their water content being brought to 85 % "field capacity" by weight. In order to avoid any contamination, that water was filtered and passed through a commercial water softener and distilled and redistilled. The final distillation was done in "pyrex" glass. In experiments where Boron was a treatment the final distillation was omitted. The experiments were conducted in the Institute's "Phytosolarium". The test plants were, a perennial grass, Paspalum commersonii (lam.), and a legume Medicago sativa(L). 115 2. EXPERIMENTAL A. Experiment I Showing chemicals used and rates applied Designation Chemicals Rate of Application/acre N 6 (NH 4 ) 2 S0 4 5 cwts. = 118 lbs. N + 135 lbs. S P 3 NaH 2 P 0 4 . 2 H 2 0 3 cwts. = 67 lbs. P + 49 lbs. Na K s . K 2 S 0 4 3 cwts. = 150 lbs. K + 70 lbs. S Ca 1 0 CaCO s 10 cwts. = 4 cwts. Ca Mgu MgS0 4 . 7 H 2 0 1 £ cwts. = 18 lbs. Mg + 22 lbs. S B« N a 2 B 4 O r 10H2O 6 lbs. = l .Olb.B + l.Olb.Na The experiment was planted with seeds on 30th September, 1958. Seedlings in excess of two per pot were removed progressively as they appeared. On 3rd November the number of plants per pot was reduced to one and the plant removed designated "thinnings" were dried and weighed to obtain some additional data of the early stage of growth. The experiment was harvested thrice viz. 25th Novem­ ber, 1958, 2nd January and 11th February, 1959. On 19th November, 2\ cwts. (NH 4 ) 2 S0 4 per acre were applied to all nitrogen treatments as these plants showed symptoms of nitrogen deficiency. A few days before the second harvest i.e. on 29th December a further 1\ cwts. of (NH 4 ) 2 S0 4 , 1£ cwts. of NaH 2 P0 4 . 2 H 2 0 and \ \ cwts. K 2 S 0 4 per acre were applied to the respective treatments. To measure the effect of Calcium on soil acidity, the pH of the soil in all the pots were determined on 24th October and 4th December, 1958. (c) Results:—All tested nutrients were found to increase yields significantly. The mean yields for the two replicates of all treatments at successive harvests are recorded in Table 2. . (a) Objective:—To measure the effect of the major nutrients N, P : K, Ca'and Mg on the growth of Paspalum commersonii (lam.). (b) Design and Procedure:—This was a 2 5 factorial experiment with two replicates of each treatment. The nutrients used and the rates of applications are enumerated in Table 1. Calcium was applied as CaC0 3 powder and mixed with the top one and a half inches of the soil in the pot. All other nutrients were applied as solutions. TABLE 1 116 TABLE 2 Experiment t—Showing mean yields for the two replicates of all treatments at successive harvests Harvest Trt atment Nil N P NP Effective Treatment Level of Signifi­ cance Nil Nil Nil K 0.01 0.02 0.02 0.01 0.03 0.06 0.07 0.18 N;P. K;Ca. 0-1% 1.0% Thinnings Age 34 days Nil Nil Ca K 0.01 0.02 0.01 0.02 0.08 0.10 0.12 0.17 Mg; N X P; P x K; P x Mg. 0 .1% J- i o % Thinnings Age 34 days Mg Nil Nil K 0.01 0.02 0.04 0.02 0.07 0.06 0.16 0.28 P, X Ca. 0 .1% J- i o % Mg Nil Ca K 0.01 0.01 0.01 0.02 0.08 0.19 0.22 0.49 Nil Nil Nil K 0.11 0.15 0.06 0.03 0.17 0.38 0.17 1.68 N ;P ; K . Ca; Mg. 0 .1% 1.0% First Age 56 days' Nil Nil Ca K 0.14 0.12 0.08 0.10 0.41 0.32 1.22 2.03 N x P;N x K. j- 0 .1% First Age 56 days' Nil Nil K 0.25 0.04 0.30 1.18 P x K; j- 0 .1% Mg Nil Nil K 0.14 0.06 0.39 2.06 N x Ca; P x Mg. 1-0% Mg Nil Ca K 0.10 0.04 0.07 0.12 0.34 0.48 1.48 4.23 Nil Nil Nil K 0.18 0.24 0.00 0.00 0.12 0.19 0.00 0.97 Second Age 94 days Nil Nil Ca K 0.16 0.12 0.15 0.19 0.19 0.17 0.00 0.77 N ;P ;K ;Ca . N x P ;N x K;N x Ca. * o.i% I 0 .1% Second Age 94 days Mg Nil Nil K 0.18 0.19 0.00 0.12 0.06 0.17 0.00 0.62 P x K; N x P x K. P x Ca; K. x Ca. o.i% I 0 .1% Mg Nil Ca K 0.27 0.12 0.24 0.29 0.18 0.24 0.00 3.91 N x P x Ca. P x K x Ca. • ' . 0 % Nil Nil Nil K 0.14 0.27 0.00 0.00 0.11 0.13 0.00 0.00 K;Mg;Ca. Third Age 134 days Nil Nil Ca K. 0.25 0.11 0.00 0.45 0.15 0.16 0.00 0.81 N X K; N x Ca. P x K; N x K. x Ca. • 1-0% Third Age 134 days Mg Nil Nil K 0.16 0.29 0.00 0.46 0.15 0.15 0.00 0.67 Mg Nil Ca K 0.27 0.16 0.47 0.49 0.25 0.25 0.00 5.81 117 Analysis of data showed that there was a marked and progressive increase in response to all tested nutrients. The pattern of response at successive harvests is shown diagrammatically in Figure I and may be summarised as follows: Figure I — Diagram showing the mean yield for the two replicates of all treatments at thinnings and the three successive harvests. Thinnings:—At this stage although the plants were only 34 days old, all the tested nutrients were responsible for high increments of yields. The effect of N, P, Mg and NP were significant at the 0.1 % level while those due to K, Ca, PK, PCa and PMg were significant at the 1.0% level. 1st Harvest:—The plants were 56 days old at this stage. All tested nutrients were responsible for high increments of yields. N, P and K were responsible for increments of 319,1,105 and 90% respectively, while Ca and Mg increased yields by 69%. All first and the second order interactions of N, P and K were significant at the 0.1 % level. 2nd Harvest:—The pattern of response at this stage was essentially similar to that at the 1st harvest, except for that due to Ca which (alone) was responsible for increments of 259%. All plants that received nitrogen without calcium, and the K nil treatments that did not receive N arid P, did not register any growth. Yields were very low in the absence of potassium, the addition of which increased yields by 290%. Mg increased yields only by 22%. All 1st and 2nd order interactions of N, P and Ca were signifi­ cant at the 0 .1% level. There was appreciable growth only in the full fertiliser treatments. 3rd Harvest:—At this stage yields were very low except in the full fertilizer treatments. Mg which had little effect at the 2nd harvest was responsible for high increments of yields (280%). (d) Discussion:—The data from this experiment shows that the sub-soil at Horekelley Estate is deficient in N, P, K, Ca and Mg. In order to get a measure of their deficiencies and also to compare the nutrient status of this soil with that of the "top-soil" the data were reanalysed and individual yields 118 in the absence of any particular nutrient was expressed as a percentage of that obtained for the full fertilizer treatments (N, P, K, Ca and Mg). The effect due to the absence of individual nutrients is shown diagrammatically in Figs. II to VI. 100 80 in Q —I UI > 604 UI > 40, 20' •NPKCaMg- — NITROGEN 2TT~ 76 §5 515 100 120 iZo • AGE IN DAYS Figure II — Diagram showing the relative yields in the absence of nitrogen at successive stages of growth. 100' 80 0 1 9 id >60 UI > _j UI OR 20 •NPKCaMg- \ — PHOSPHORUS \ \ \ \ 20 ZD BD §0 100 W AGE IN DAYS Figure III — Diagram showing the relative yields in the absence of phosphorus at successive stages of growth. 119 1001 NPKCaMg' \ 8 0 \ X — POTASSIUM 9 \ « 6 0 \ ui > U I or 20' 0 AGE IN DAYS Figure IV — Diagram showing the relativejyields in the'absence of potassium ati successive stages of growth. 2"o Zo 55 35 loo i55 wo ; AGE IN DAYS Figure V — Diagram showing the relative yields in the absence of calcium at successive stages of growth. 120 20 Ho grj 3b" ""ibo T20 So" AGE IN DAYS Figure VI — Diagram showing the relative yields in the absence of magnesium at successive stages of growth. The effect due to the absence of individual nutrients may be summarised as follows:— Nitrogen:—In the absence of nitrogen, yields decreased by 63 % at the thinnings stage. Thereafter the relative yields declined steadily for the three harvests from a value of IS at the 1st harvest to 9% in the 3rd harvest. Phosphorus:—Phosphorus was found to be acutely deficient in the sub-soil. Even at the thinnings stage the relative yields were as low as 6 and dropped further to 3% at the 1st harvest. However, from then onwards the relative yields increased steadily through 8 at the 2nd to 19% at the 3rd harvest. This indicates an increase in the available P with age. Such a decreasing response to P at successive harvests has been recorded for the surface soil showing that there is essentially no difference in the response to P in both layers. Potassium:—In the absence of K relative yields decreased steadily at successive harvests from an initial value of 52 at the thinnings stage through 46 in the 1st to zero in the 2nd and 3rd harvests. All plants in the N treatment that did not recieve P, K and Ca and also those plants in the N treatments that received P but not K died after the 1st harvest. Although there was a steady decline in the relative yields in the absence of K in the surface soil at successive harvests, they did not reach zero even after 140 days. Calcium:—In the absence of Ca relative yields declined steadily at successive harvests from an initial value of 38 at the thinnings stage through 37 at the 1st and 25 at the 2nd to 9% at the 3rd harvest. This low relative yields in the 3rd harvest is mainly due to the death of plants in the Ca 0 pots that received 121 nitrogen (Ca„N5). The death of plants in such treatments may be due to two reasons; either, lack of Ca in sufficient quantities for proper growth, or, due to the lowering of soil pH due to the application of (NH 4 ) 2 S0 4 . The pHs determined during the course of the experiment are recorded in Table 3. TABLE 3 Experiment I—Showing mean pH values of nitrogen and calcium treatments Date Treatment Nil CaC03 24.10.58 Nil 5.58 6.67 (NH 4 ) 2 S0 4 5.19 6.32 4.12.58 Nil 5.69 6.66 (NH 4 ) 2 S0 4 4.84 5.83 Magnesium:—In the absence of Mg relative yields remained steady at 33 % up to the 2nd harvest. However, at the 3rd harvest it dropped to 11 %. This was essentially similar in pattern and magnitude to that obtained with the surface soil. B. Experiment II (o) Objective:—-To measure the effect of N, Ca, B and Mo on the growth of Medicago sativa (L). (b) Design and procedure:—This was a 2 4 factorial with two replicates of each treatment. The forms and rate of application of these nutrients used are enumerated in Table 4. All pots received a basal dressing of P 3 , K 3, Mg t , Fe 7, Cu 7, Mn 7 and Zn 7. TABLE 4 Experiment II—Showing chemicals used and their rates of application Designation Chemical Rate of application/acre N 3 N H 4 N 0 3 3 cwts.= 118 lbs. N Ca 1 0 CaC0 3 10 cwts. = 4 cwts. Ca B 6 Na 2 B 4 Cy 10H.O 61bs. = 1 lb.B + 1 lb.Na Mo 2 ( N H 4 ) a M o 7 0 2 4 . 4 H 2 0 2 lbs. = 1 lb. Mo + 0.141b. Na Fe 7 FeS0 4 .7H s O 7 lbs. = 2 . 4 lbs. Fe + 0.8 lb. S Cu 7 CuS0 4 . 5H„0 7 lbs. = 1.8 lbs. Cu + 0.91b. S Mn 7 - MnS0 4 . 4H,0 7lbs. = 1.8 lbs. Mn + 1.01b. S. . Zn 7 ZnS0 4 . 7H 2 b 7 lbs. = 1.5 lbs. Zn + 0.8 lb. S 122 This experiment was planted on 15th November, 1958. There was no germination in the Ca-Nil treatments and was very poor in the N-Nil treatments. The experiment was therefore reconstituted to test B and Mo; N and Ca being made basal treatments. Due to the insufficiency of the calcium added, the seedlings turned pale, and finally died. Therefore, on 22nd June, 1959, a further 10 cwts. of CaC0 3 was added and fresh seeds planted. Germination was very poor in the B-Nil treatments. In September, the plants showed signs of withering indicating inadequacy of the added Ca, and a further 10 cwts. of CaC0 3 were added on 10th October. At this stage all pots had received a basal dressing of 30 cwts. ofCaCOg/acre. The experiment was harvested thrice, viz. on 2nd October, 19th November, 1959 and 12th January, 1960. During the course of the experiment any other nutrients found deficient were added. The nutrients added were as follows:— 27.10.59. — 3 cwts. N H 4 N 0 3 per acre. — 3 cwts. K 2 S 0 4 per acre. 14.11.59 — 3 cwts. N H 4 N 0 3 per acre. (c) Results:—In all harvests there was a very big response to B. Mo had no effect on yields at any stage. The deficiency of B was so great that there was practically no growth in the B-Nil treatments. The mean cumulative yields for all harvests of all treatments are recorded in Table 5. TABLE 5 Experiment II—Showing mean cumulative yields of all treatments for all harvests Nil Mo B MoB 0.29 0.39 2.85 1.95 UI) Discussion:—The data from the experiment indicate that this soil is acutely deficient in Ca and B. It has been reported that the surface soil was also acutely deficient in these two nutrients. C. Experiment III (a) Objective:—To measure the effect of Fe, Cu, Zn and Mn on the growth of Paspalum commersonii (lam.). (b) Design and procedure:—This was a 2 4 factorial experiment with two replicates of each treatment. The forms and rates of application are the same as in Experiments I and II (Tables 1 and 4). This experiment was planted on 26th November 1958 and harvested thrice, viz. on 2nd January, 11th February and 16th March, 1959. (c) Results:—None of the tested nutrients except Zn and Cu had any effect on yields. Zn which was responsible for a slight increase in yields in the 1st harvest, depressed yields in the 2nd and 3rd harvests. This negative response was significant at the 1.0% level at the 3rd harvest. Cu was responsible for slight increments of yields at the 3rd harvest which however was not significant. The mean yields for the two replicates of all treatments are recorded in Table 6. 123 TABLE 6 Experiment HI—Showing mean yields for the two replicates of all treatments at successive harvests Harvest Treatment Nil • Zn Mn ZnMn Nil 2.52 3.97 3.90 4.77 Nil Cu 2.45 2.74 2.07 3.49 1st 1st Nil 3.25 3.14 2.67 2.94 Fe Cu 2.71 2.81 2.94 3.11 Nil 3.65 2.00 3.07 2.89 Nil Cu 3.13 2.71 2.32 2.01 2nd 2nd Nil 2.81 2.26 3.33 1.76 Fe Cu 3.50 2.92 2.64 2.47 Nil 3.51 2,64 2.73 • 1.62 Nil Cu 3.99 3.28 3.24 2.31 3rd 3rd Nil 4.01 2.76 3.75 1.09 Fe Cu 3.33 3.22 3.22 2.52 (d) Discussion:—The data from this experiment shows that there is no effect due to any of the tested nutrients at the early stage of growth. However, the slight response due to Cu at the later stages indicates an incipient deficiency of this nutrient. Similar results have been obtained with the surface soil. 3. SUMMARY AND CONCLUSIONS The three experiments carried out with the sub-soil indicate an acute deficiency of N, P, K, Ca, Mg and B. The surface soil was also found to be deficient in all these nutrients. 4. ACKNOWLEDGEMENTS The authors wish to express their sincere appreciation of the help rendered by all members of the Division of Agrostology. The diagrams were photographed by Mr. B. Hettiarachchi and the typescript was prepared by Miss H. Jayasinghe. 5. REFERENCES 1. Paltridge, T.B. and Santhirasegaram, K.—1957 C.R.I. Bulletin No. 12. 2. Paltridge, T.B. and Santhirasegaram, K.—1957 C.R.I. Bulletin No. 13. 124