74 AGRICULTURAL SECTION

Mr. N. V. Mohan Rao presented the following paper.

Paper

SOME ASPECTS OF NITROGEN NUTRITION OF SUGARCANE IN ANDHRA

N.V. MOHAN RAO AND R. L. NARASIMHAM

Sugarcane Research Station, Anakapalle, India.

INTRODUCTION

Sugarcane is one of the most important commercial crops in Andhra State and plays a vital role in the agricultural economy of the cultivator. It occupies an area of abopt 1,20,000 acres and shows indications of further increase ; over 80 percent of the area under cane is occupied by Co. 419. With eight sugar mills having a total crushing capacity of about 5,000 tons of sugarcane per day and producing over 40,000 tons of white sugar annually, the sugar industry has come to stay as the foremost in the State and stands fourth in the Indian Union. While approximately 17 to 18 per cent of the cane grown goes to production of sugar, about 65 to 70 percent is converted into crude sugar made in the form of moulds, called Jaggery or Gur, which finds wide use for domestic consumption in place of &gar and is also exported to a considerable extent.

Manuring is one of the most potent factors to step up yields of sugarcane and forms a major item in its cost of cultivation. Of the three major plant-food elements, sugarcane responds most to nitrogen in this State, no perceptible effects being observed in the case of potash and phosphoric acid. The total dose of nitrogen varies from about 100 lbs. per acre in the northern to about 200 ibs. in the southern and central districts. Taking about 150 lbs. nitrogen per acre as the average for the State, the annual-requirement of nitrogenous fertilizer taken as ammonium sulphate works out to about 45,000 tons, involving an expenditure of approximately fifteen million rupees. The need for a scientific and rational schedule of fertilization in the interest of national economy is thus apparent.

Studies were, therefore, directed to elucidate in detail the various biochemical aspects of nitrogen nutrition of sugarcane with particular reference to this tract; the effects of different doses, forms, and times of application of nitrogen on the qualitative and quantitative aspects of sugarcane production are discussed in the following pages. Preliminary studies conducted on the possibilities of the "foliar

N.V. MOHAN RAO, R,L. NARASIMHAM

~ r ~ t y of the area. The alluvial delta soils of Godavari and Krishna are fertile ell-supplied in plant nutrients, showing some deficiency of nitrogen ; all sugarcane soils are more deficient in nitrogen and organic matter. The soils of the semi-arid inland districts are heavy clays, alkaline in reaction

The climatic conditions of the State represent a transition from the sub- a1 Northern India to the hot and humid South ; the distribution of rainfall from about 40 to 45 inches in the northern districts to about 20 to 25 inches southern and central districts. The rainfall is received in two precise

-December). Highest summer temperatures are recorded in the months -May, while the dry and chill winter usually lasts from December to

The meteorological data for Anakapalle*, the main centre of sugarcane

TABLE I

December 84.3 62.8 64 0.81 1

Total for the year 39.53 59

*with a rainfall of 0.1 inch and over,

-- --

76 AGRICULTURAL SECTION

The soils of the Anakapalle tract are representative of the well-drained loams of the Northern districts ; analysis of the top one-foot soil is given in Table 11.

TABLE I1

PH 7.2 Mechanical analysis : Total nitrogen 0.0434% Moisture Organic carbon 0.42% Clay Lime 0.46% Silt Available PzOs 0.022% Coarse and fine sand Exch. calcium 14.4 m. eq. per 100 gm. Water soluble salts 0.053%

Sugarcane is normally planted in the months February-April, and harvested after a year ; after completion of germination and tillering, active growth commeiices from June and extends till December, coinciding broadly with the mci:lsoons, after which maturity sets in.

REVIEW OF LITERATURE

The role of nitrogen fertilization in the production of sugarcane has received probably the greatest attention in agronomic research on the crop. Earlier work by Das (ll), and Das and Cornelison (12) showed that higher nitrogen doses increased elongation, tillering, leaf-width, and succulence of the plant ; while the sucrose per cent in juice was depressed, the glucose, alcohol soluble as well as total nitrogen and the mineral matter in the same showed an increase. Ayres (4) reported that sugarcane absorbed potash and silicon to a much greater degree than nitrogen and phosphorus and this absorption was governed by the stage of developnlent of the plant ; he also found that the highest concentratioil of these elements in the dry matter of the plant occurred at three months age and that, while the rate of absorption of nitrogen diminished after reaching a maximum by about six months, that of' calcium, magnesium, phosphorus and potash continued to increase till a far later age. Kobus (21) reported from Java that nitrogen absorption was most rapid under those conditions upto 8 months of age, followed by a decrease. ~ o r d e h (6,7,8,9,10) elaborated the studies on nitrogen nutrition of sugarcane in Hawaii; he stated that ilitrogen increased the same in all parts of the plant, particularly the foliar tissues and the nitrogen content declined with age. The total green and dry weight of the plants and also the green tops generally increased with higher nitrogen application, the effect of the initial increments of nitrogen being more marked. Nitrogen also depressed arrowing and tended to promote lodging in cane. Borden (5) also reported oil the role of climatic conditions, particularly light and temperature, on nitrogenutilisation, stating that deficiency of the same retarded growth. The results from fertilizer experiments conducted in the Dominican Republic and South Africa were recently reviewed by Aughtry et a1 (3), and Du Toit (14); Innes (19) dealt .with the inorganic

N.V. MOHAN RAO, R.L. NARASIMHAM 77'

from nitrogen in all the cane-tracts, while potash and phosphoric acid

under nitrogen deficiency and that the optimum uptalte of nitrogen,

scussed by Lakshrnikantam (22), who reported that they did not come to the eve1 of concentrates in respect of nitrogen nutrition ; similar observations were

also made by Rege (32). Parthasasathy and Lakshmiltaniam (30) reviewed. the fertilizer experiments with nitrogenous manures on sugarcane in Madras and observed that under low soil moisture conditions, organic ilitrogenous manures were better suited, while ammoniunl sulphate was effective under a comparatively more plentiful water supply.

EXPERIMENTAL DETAILS

Detailed investigations on the influence of graded doses of nitrogen on the uptake of the same by the cane plant, dry'matter production and the ultimate yield of cane and sugar were conducted in a field experiment during the years 1948-49 to 1950-51. The layout was one of split-plot design, with two varieties,

Plant samples (above-ground portion) were drawn by the Unit Length

AGRICULTURAL SECTION

+ the effects of the treatments on the soil fertility, alialysis of the same was conducted before and after harvest of the crop, adopting the usual ailalytical methods. (1,31).

Detailed juice analysis for the sugar and noa-sugar constituents was conducted on composite samples for the respective treatments, following the procedures given by A.O.A.C. (I), Fort and McKaig (16), Kharin and Srniriiova (20), and Spencer and Meade (38):

The data collected are presented and discussed hereunder.

RESULTS AND DISCUSSION

INFLUENCE OF NITROGEN ON CROP PERFORMANCE

(i) Uptake of nitrogen by the crop:-The data for the nitrogen content of the plant (varieties Co. 527 and Co. 419), as influenced by the different doses of nitrogen are presented in Table 111.

TABLE 111

NITROGEN-CONTENT OF STEM AND WHOLE-PLANT (% DRY MATTER) (March-plantyd crop)

Treatments* June July Aug. Sept. Nov. Jan. March

C0.527 : 100N S - 0.78 0'65 0'52 0'32 0'34 - P 2.11 1.18 0.78 0.87 0.60 0.48 0.42

do 150N S - 0.81 0.89 0.52 0.45 0.35 P 2.13 1.18 1.03 0.87 0.67 0.50 0.42

do 200 N S - 0.78 1.03 0.67 0.55 0.49 - P 2.31 1.22 1.13 0.96 0.81 0.76 0.46

CO. 419: 100N S - 0.70 0.50 0.35 0.29 0.32 - P 1.94 1.21 0.98 0.61 0.52 0.49 0.29

do 150N S - 0.71 0.74 0.37 0.39 0.35 - P 2.19 '1.10 1.09 0.72 0.58 0.55 0.29

do 200N S - 0.79 1.02 0.38 0.42 0.39 - P 2.00 1.09 1.08 0.71 0.62 0.57 0.36

*S : Stems alone ; P : Whole plant.

The nitrogen-content of the stem tended to show a slight increase upto August, especially in the higher nitrogen doses, and later followed the same trend as whole-plant. The nitrogen concentration in the plant was highest in the early stages, the youngest plant having the maximum nitrogen percent dry matter. There was a fall in the nitrogen concentration with age, under all conditions, that at the "boom stage" being most rapid, indicating the rapid utilisatioil by the growing crop at this stage (Fig. I). The necessity for maintaining high concentratioil of nitrogen in the plant in the early stages of growth has often been

80 AGRICULTURAL SECTION

In spite of the higher nitrogen concentration in the plant, the actual uptake per acre in the early formative stage was the lowest; the nitrogen uptake rapidly increased with the onset of the grand-period of growth (from June), and by about six months age it was found that a inajor portion of the total uptake was completed (Fig. 1). The weather conditions, with increase in the rainfall and humidity, attended with the favourable temperature at this period could also be seen to be most suitable for rapid growth of the crop (Table I). The maximum uptake of nitrogen was completed by about October-November, whereafter a fall in the same was noted. The period of growth from about 3 to 6 months age of the crop, corresponding to that of the most rapid uptake of nitrogen, appeared to be the most "critical period" from the standpoint of nitrogen nutrition, and a correct manurial schedule should envisage supply of ample amount of available nitrogen to the growing crop during this period. The results of Asana (2) also indicated that the rate of nitrogen uptake increased to a maximum in about 17 weeks after which there was a decline; Rege and Sannabhadti (34) observed that in the Bombay- Deccan the major portion of the nitrogen-uptake was completed by about six to seven months after planting, that of phosphoric acid and potash extending till harvest time.

Higher doses of nitrogen in general resulted in a higher uptake of the same by plant, but the fact that this was not reflected in increased yield indicated the limits to its utilisation by the crop beyond 100 lbs. per acre. An important obser- vation was that the early variety, Co. 527, completed the major uptake of nitrogen earlier than Co. 419, the late variety, other conditions being similar. This pointed to the need for early manuring to early varieties as compared to late ones; actually increased yield without detriment to juice quality was achieved on this Station, with a few low-yielding early varieties, by completing the manuring within two months from planting (23).

(ii) Growth and dry-matter production:-The rate of growth of the variety Co. 419, as determined by periodical height measurements, under graded doses of nitrogen was studied by Lakshmilcantam and Sankaram (24) on this Station; they observed that manuring gave an initial advantage in growth prior to July and that growth (average height) of individual canes was definitely retarded below 100 lbs. nitrogen per acre, doses beyond this resulting in no further improvement.

The periodical variations in the dry-matter production, calculated from the fresh weights of plants per unit area and the moisture content, are &own in Table V.

AGRICULTURAL SECTION

The data disclosed that the most rapid increase in the dry-matter accumu- lation in stems occurred from August to November for both the varieties ; this was almost in succession to the period of most rapiduptake of nitrogen and indicated immediate utilisation of the same for plant growth. No clear differences in the dry-matter production in respct of leaves could be seen. Similar results were reported by Rege and Sannabhadti (34), who found that nutrient absorption took plaae at a much greater rate than the 'elaboration of dry-matter in the early states of growth. Co. 419 showed a further accumulation of dry matter even upto January, which must have contributed to its higher yield. Higher doses of nitrogen tended to increase the dry matter production of Co. 419 only in the early stages, while the effects on Co. 527 were not marked.

The moisture-content of plants was highest in the active growing period and declined towards maturity, that for Co. 527 being still earlier. Higher doses of nitrogen resulted in a slight increase of plant-moisture. Co. 527 was found to record almost throughout a lower moisture-content than Co. 419 and as ;eported by Parthasarathy and Ramarao (29), this might haye induced its earlier maturity. A study of the ratio of fresh weights of stems to leaves at periodical intervals $isclosed a progressive increase till harvest, as reported by Dillewijn (13), Co. 419 exhibited throughout a higher ratio than Co. 527, this being consistent with the higher rate of stem-production in this variety and its higher moisture. The effects of the different nitrogen doses were found tp be erratic.

(iii) Cane and sugar yields :- Thq yield of cane and sugar calculated per acre are given in'~ab1e VI, bei

average for the three seasons, 1948-49 to 1950-51; a spmmary of the results

TABLE VI

YIELD OF CANE AND SUGAR (Average for 3 years)

Treatments

Co. 527 -100 Ibs. N 0.411 0.0413 -do- -150 lbs. N 0.289 0.0304 -do- -200 lbs. N 0.214 0.0202

(20.419 -100 Ibs. N 46.15 5.34 31,780 . 0.462 0.0534 -do- -150 lbs. N 32,150 0.311 0.0347

-do- -200 lbs. N 30,580 0.217 0.0240

consiste moistu~

N.V. MOHAN RAO, R.L. NARASIMHAM 83

TABLE VI (Contd.)

The late variety, Co. 419, gave significalltly higher yield of cane over Co.527 in two out of the three seasons; the three levels of nitrogen, viz., 100 lbs., 150 lbs., 200 lbs., nitrogen per acre did not differ significantly in respect of cane- yields. The recovery of cane and sugar per pound of nitrogen top-dressing was higher for Co. 419. The lower yield of cane and sugar per pound of nitrogen top-

aEysi~ of cane-yield data

S. E, of treat- Critical diffe- Signi- ment mean rence (P=0.05) ficance

1.36 tons , 4.94 tons No 1.16 ,, 4.22 ,, Yes 0.59 ,, 2.14 ,, Yes

1.38 ,, 4.08 ,, No 1949-50 1.41 ,, 4.17 ,, NO

0.74 ,, 2.19 ,, No A

sis by co-variance.

Co. 419 recorded 011 average higher girth and lefigth of individual cailesj though the average internodal length was more for Co. 527. The nitrogen- effects were not so marked except for a slight-increase in length of cane, with higher manuring. Co. 527 had a higher stalk-population per acre at harvest than r o . 419.

dressing in the case of the higher doses above 100 lbs. per acre indicated the futility of the same from the ecoliomic standpoint. I11 view of this, as also due to lack of response by way of increased outturn, the dose of 100 lbs. nitrogen per acre was taken to be the optimum economic dose fos this tract and this was in conformity with the earlier results of Lakshmilcantam and Saaltaram (24) on this Station.

(iv) Soil analysis :- Analysis of the top one-foot soil at the start and after harvest of the crop

was conducted during all the seasons. As reported by the authors earlier (27), there was no depletion of nitrogen beyond the initial level under any of the treatments and while the soil reaction (pH) and available phosphoric acid were apparently unchanged, the organic carbon tended to show an increase after cane.

$ :s; INFLUENCE OF NlTROGEN ON THE COMPOSITON OF THE JUICE.*

While the effects of nitrogen fertilization on the yield aspects of sugarcane have been studied in great detail as reported earlier, comparatively less information is available on its effects on juice composition. This is of particular importatlce to Indian conditions, where a large portion of the cane grown goes to the

*The data for this section have been omitted, but diagrammatically presented in Fig. 2,

84 AGRICULTURAL SECTION

man~~facture of gur. Unlike in sugar manufacture, where clarification of the juice is a well-controlled chemical process, gur-malting is comparatively crude and no facilities exist for an efficient removal of the impurities from the mother liquor. An understailding of the occurrence and elimillation of the so-called non-sugar impurities in juice thus poses as a major problem from the standpoint of gur. Studies conducted on different aspects of nitrogen fertilization to sugar- cane in relation to juice compositioh are broadly discussed llereunder, the variety under study being Co. 419 throughout.

(i) Graded doses of nitrogen :- L

The effects of 100 lbs., 150 lbs. and 200 Ibs. nitroge~l on the composition of the juice of Co. 419 at twelve months age was studied in detail. The data revealed a depression in the sucrose and an increase in glucose and organic non- sugars in juice in the higher nitrogen doses, particularly 200 lbs. per acre. Though the nitrogen doses did not produce any differential effect on the total ash and lime, the phosphate content was depressed and an increase jn ilitrogen was noted in the higher doses, thereby giving higher values of NIP, 0, ratio for the same (Fig. 2A). The depression of phosphate in juice under higher doses of nitrogen beyond opti- mum has been reported by Borden (9, lo), Rege and Basu (33) and Evans (1 5). These were noted to be detrimental to efficient clarification of the juice, resulting in gur of poorer colour and structure, which was more marked under 200 lbs. nitrogen dose. The effects of nitrogen on the physical cl~aracteristics, chemical composition and the keeping qualities of gur were discussed by the authors

(ii) D~fferent forms of nitrogen :- The effect of the following forms of nitrogenous manures all applied to

supply 100 lbs. nitrogen per acre, on the detailed composition of the juice of Co. 419, was studied :-

1. Ammonium sulphate. (A.S.) 2. Groundnut cake (G.N.C.) 3. Mixture of ammonium sulphate and groundnut cake in proportion

of 1 : 2 on nitrogen basis. (Mix.) 4. Farmyard manure. (F.Y.M.)

The "farmyard manure" treatment gave better juice quality as compared to the concentrates and even among the latter, lower purity and higher glucose were recorded wherever ammonium sulphate was used. The inorganic fertilizer, ammonium sulphate, was noted to ii~crease the non-protein as well as total nitrogen and colloids in the juice, while the phosphate was depressed. On the other hand, the bulky organic manure gave the highest phosphate, lowest nitrogen and colloids (Fig. 2B). Thus the N/P,O, ratio, which was known to affect gur quality, was lowest for "farmyard manure" and higher wherever ammonium sulphate was included. In conformity with this, the best quality gur was reco- vered from juice under the farmyard manure treatment.

The cane-yields, however, were significantly higher for the concentrates, as compared to "farmyard manure", indicqting the poorer nitrogen supplying

N.V. MOHAN RAO, R.L. NARASIMHAM

of the latter (Table VIII). The need for a combination of organic and c nitrogen for recovery of best quality gur was thus indicated.

) Time of application of nitrogen :-

. B: 50 lbs. N at 14 months and SO lbs. N at 44 months.

C : 50 lbs. N at 14 months and 50 lbs. N at G months. D: 50 Ibs. N at 3 months and 50 Ibs. N at 44 months. 1

5. , E: 50 lbs. N at 3 n~onths and 50 lbs. N a t 6 months.

5UCR036 va NlTR00bN (~4 DHOSPH

v

86 AGRICULTURAL SECTION

applications of nitrogen were known to depress sucrose in juice, very late manuring, viz., at six months after planting did not appreciably lower thel sucrose and purity or increase glucose-content, ,even to the extent of application at 49 months. Similar findings were reported by Laltshmikantham (23) on this Station and by Evans (15) in Mauritius. This is brought out further by the relative amounts of non-protein and total nitrogen in the juice. The delayed nitrogen dressings resulted in higher non-protein nitrogen in the juice; and the application at 6 months

, was found to correspond to the highest accumulation of this constituent, which was almost half of the total nitrogen (Fig. 2C). This seemed to indicate that the nitrogen from such late applications tended to remain at lower stages of protein metabolism and for this reason, did not interfere in normal maturation of the crop, brought about by other environmental factors. Evans (15) also found that a "late heavy dressing" of nitrogenous fertilizer, did not produce any significant difference in the sucrose, as compared to the normal dressing, while there was a three-fold increase in the nitrogen content of juice.

FERTILIZATION CONTROL

The foregoing studies thus indicated the importance of optimum nitrogen fertilization to cane at the proper time, from the standpoint of cane production as well as juice quality and pointed to the need for a proper fertilization control. Pioneering work in many sugarcane-growing countries, particularly Hawaii, showed the green leaf portion of the cane plant to be the most representative part for diagnosing its nutrient status and as a guide for fertilization. Innes (18) reported on a survey of the fertility status of some of the cane plantations in Jamaica through a regular leaf-nutrient study. Yuen and Hance (40) andBorde (6, 7, 8, 9, 10) in Hawaii, Halais (17) in Mauritius, Samuels et a1 (36) in Puert Rico, and Innes (18) in Jamaica described the foliar diagnosis techniques adopte

for controlling nitrogen fertilizati,on.in Hawaii, the third leaf is chosen for the test in Mauritius and Jamaica where the cane is of a much shorter duration tha Hawaii.

In the present study also, the third leaf was chosen as the unit of study; the lamina portion at about the middle of the leaf was sampled and the total nitrogen

about four to six months age of the crop appeared to be the most optimum

N.V. M O H ~ N RAO, R.L. NARASIMHAM 87

Doses oj7 nitrogen :-

Variations in leaf (punch)-nitrogen under graded doses of nitrogen applied, 0 Ib., 100 lbs., 200 Ibs., and 300 lbs. per acre were studied during the years

TABLE VII

LEAF-NITROGEN UNDER GRADED DOSES APPLIED (CO. 419) t (Averge for 3 seasons)

Leaf nitrogen percent dry matter

44.24 4.86 2.14 2.08 1.97 1.94 1.72 1.51 46.42 5.02 2.27 2.25 2.07 1.95 1.82 1.51

Differences in leaf nitrogen as affected by the manurial treatments began to

gen per acre to be the economic optimum dose for this tract. On this , the data indicated that the leaf-nitrogea corresponding to tliis dose might be tively taken as the optimum for securing dormal cane-tonnage, there being no r limiting factors affecting yield ; for the foiirth month age of the crop, this 2.0 to 2.1 % dry matter, values above this repfdsenting luxury revels (Fig. 3A).

(iii) Forms of nitrogenous manures :- The data on leaf-nitrogen and yield of cane and sugar as influenced by

ifferent forms of nitrogenous manures are presented in Talble VIII, being averages for the two seasons, 1951-52 and 1952-53.

The treatments, ammonium sulphate, groundnut cake and their mixture recorded sigiliiicantly higher yield of cane over "farmyard manure" and "no manure" treatments, though the manures were all applied to supply 100 lbs. &trogen Per awe in the case of the treatments 1 to 4. This indicated the comparatively

88 AGRICULTURAL SECTCON

TABLE VIIl

LEAF-NITROGEN UNDER DIFFERENT FORMS OF NITROGErJ (CO. 419) (Average for 2 seasons)

Yield per acre Leaf nitrogen percent dry matter Details (100 lbs. nitrogen) Cane Sugar 3rd 4th 5th 6th Har-

(tons) (tons) month month month month vest -

Ammonium sulphate 39.41 5.21 2.16 1.99 1.79 1.79 1.41 Groundnut cake 38.65 5.43 2.06 1.99 1.94 1.81 1.21 *Mixture 39.23 5.15 2.08 2.01 1.93 1.79 1.42 Farmyard manure 29.85 4.30 1.79 1.57 1.52 1.42 0.88 No manure (0 lb. N) 26.14 3.86 1.76 1.53 1.46 1.36 0.77

poorer nitrogen-supplying capacity of farmyard nianure, as reported by Rege (32). There was a sharp increase in the leaf-nitrogen under the concentrates over

Nt ' 4& MONTH *.= 5& M o m

I L

15 1 5

316.3 21, GRllBED DOSES OF NITROGEN.

LERF-NB AT N, 4th MONTH NZ' 5& MONTH

FIG 38.. DIFFERENT PQRMS QF NITROGEN ' A6.3 - LEflF-NITROGEN ANDYIELD OF C13NE a~lD SWGBA

(VARIETY - co 419)

-

N.V. MOHAN RAO, R.L. NARASIMHAM 89

farmyard manure" and "110 manure" treatments, while the three concentrates did ,lot differ much among themselves in respect of leaf-nitrogen (Fig. 3B).

Talting the yield from the concentrates at 100 lbs. nitrogen level as the optimum, the corresponding leaf-nitrogen values were taken to represent the optimum for the particular ages of the crop and these were noted to be similar to those under graded doses reported earlier. The corresponding figures for "farm- yard manure" treatment were talcen to indicate deficiency values ; at the fourth month these were about 2.0% for optimum and 1.6% for deficiency conditions.

Preliminary examination of the leaf-nitrogen data for the different years indicated that under optimum and below optimum conditions the leaf-nitrogen

throughout the growth period were highly correlated with cane-yields, while with excess doses it was not so.

( i i i ) Time of application of nitrogen :- The variations in leaf-nitrogen as influenced by the time of application of

itrogen were also talten up for study as it is in vogue in some parts of the State to apply large doses of nitrogen to cane with the expectation of the normal returns. The data are given in Table IX.

TABLE IX

LEAF-NITROGEN FOR DIFFERENT TIMES OF APPLICATION O F NITROGEN

(Co. 419-March-planting)

Leaf nitrogen per cent dry matter Nitrogen at 100 Ibs. Yidd in tons per acre Har- per acre applied as Cane Sugar June Aug. Sept. Nov. vest

50 N at 14 months & 41.94 5.03 2.20 2.17 2.00 1.69 1.37 50 N at 3 months

0 N at I t months & 41.55 4.50 2.30 1.93 2.02 1.80 1.36 i 0 N at 44 months 0 N at I t months & 41.39 4.93 2.30 2.01 1.89 1.80 1.34

50 N at 6 months 50 N at 3 months & 40.56 4.39' 1.96 2.22 2.11 1.83 1.27 50 N at 44 months 50 N at 3 months & 40.23 4.17 1.96 2.12 2.08 1.90 1.51 50 N at 6 months 50 N at 48 months & 38.82 4.29 1.96 1.87 1.57 1.79 1.38 50 N at 6 months No manure (0 lb. N) 34.72 4.32 1.96 1.87 1.58 1.48 1.22

The data indicated that the highest leaf-nitrogen was recorded when the manuring was completed by three months ; the rise in leaf-N after the manuring was considerably lower as the time of application was delayed. There was a comparatively lower response to the dose given at six months, more so if the plant was altogether starved for nitrogen till late (4h months). The trend of the

90 AGRICULTURAL SECTION

cane-yield for the respective treatments was also similar. Though the yields of cane did not differ significantly for the tiines of application, higher yield was in general recorded when the total dose was given by 48 months, while the doke given at six months was least effective in pulling up the yield. The data indicated that if for any reason manuring was to be delayed, it would be more useful to give at least a part dose in the early stages for better utilisation of later application, than starving the crop altogether for nitrogen till late in the season.

SUMMARY

(1) Sugarcane responds most to nitrogen in Andhra State, the optimum dose varying from about 100 lbs. to 200 lbs. nitrogen per acre. The effeqts of different doses, forms and times of application of nitrogen on the uptake and utilisation of the same by the crop and on the composition of the juice are discassed in the paper. The results of preliminary studies on the variations in foliar- nitrogen under these conditions are also outlined.

(2) In the studies on Co. 527 and Co. 419, manured at 100 lbs., 150 lbs., and 200 lbs. nitrogen per acre, i t was noted that the nitrogen content of the plant increased with increased doses. This was highest in the early stages and gradually declined with age, the fall a t "boom stage" being most rapid. Among the two varieties, Co. 527 recorded a higher nitrogen in plant than Co. 419, which, how- ever, was found to be more efficient in the utilisation of nitrogen for growth.

(3) Uptake of nitrogen by the crop per acre was lowest in the formative stage and was completed by about October-November again showing a decline by harvest time. The most rapid rate of nitrogen-uptake occurred from 3 to 6 months age of the crop, which represented the "critical period" for nitrogen- requirement. The early variety, Co. 527, was found to complete the maximum uptake of nitrogen earlier than Co. 419. The rate of dry matter accumulation in the plant was highest in the period immediately following that of rapid nitrogen- uptake. Co. 419 gave significantlyhigher cane-yield than Co. 527, but the three levels of nitrogen did not differ in respect of the same. Considering the lower yield of cane and sugar per pound of nitrogen-topdressing beyond 100 lbs. per acre, as also lack of response by the crop, this was taken to be the economic optimum dose for the tract.

(4) In the studies on the effect of nitrogen on the composition of juice of Co. 419, higher doses beyond optimum depressed the sucrose, increased glucose, organic-non-sugars and nitrogen in juice; while the total mineral matter was unaffected, the phosphate content was lowered, which was detrimental for good clarification in gur-making. Among the forms of nitrogenous manures tried, farmyard manure gave better juice quality than concentrates, recording the highest purity, highest phosphates and lowest non-protein and total nitrogen. The reverse was the case wherever ammonium sulphate was included, thus indicating the need for a proper combination of organic and inorganic nitrogen for

I N.V. MOHAN RAO, R.I.. NARASIMHAM

rose-content in juice was not appreciably depressed inthe case of the nitrogen

the foliar diagnosis technique to judge the nutritional status of the plant

leaf-N corresponding to 100 lbs. N per acre (about 2.0-2.1% at the fourth th) appeared to be optimum for securing normal yields. Application of

nitrogenous concentrates like ammonium sulphate resulted in a much higher leaf- nitrogen than bulky ~rganic manure (farmyard manure), which recorded sigliificantly lower yield. The leaf-N values for "farmyard manure" treatment (about 1.6% at the fourth month) indicated deficiency level. Leaf nitrogen in early growth period was highly correlated with cane yield under optimum or below optimum conditions of nutrition.

(8) Application of the total dose of nitrogen within three months after planting gave the highest leaf-nitrogen (Co. 419). There was a comparatively lower uptake of nitrogen (response in the leaf-N) from the dose given at six months more so if the plant was altogether starved for N in the early stages. The trend of cane-yields was also similar, the delayed dose of nitrogen given at six months do

ACKNOWLEDGEMENT

REFERENCES

1950 Official and Tentative Methods of Analysis. (Washington, O.C., U.S.A.)

2. Asana, R.D. 1949 The absorption of nitrogen by the sugarcane plant at different stages of growth. Ann. Bot. N.S., 13, p. 238'.

Indies, pp. 60-68; and pp. 3-16.

1937 ~bsorption of mineral nutrients by sugarcane at. suc~essive stages of growth. Haw. Plant. Rec., 41, pp. 335-351.

9 2 AGRICULTURAL SECTION

5. Borden, R.J. 1936 Cane growth Studies. The dominating effect of climate. Haw. Plant. Rec., 40. pp. 143-156. I

6. Borden, R.J. 1942 A search for guidance in the nitrogen fertilization of the sugar- cane crop. I. The Plant Crop. Haw. Plant Rec., 46. pp. 191-238.

7. Borden, R.J. 1944 -do-. 11. The First Ratoon Crop. Haw. Plant. Rec. 48. pp. 271-306.

8. Borden, R.J. 1946 -do -- 111. The Second Ratoon Crop. Haw. Plant. Rec. 50. pp. 161-200.

9. Borden, R.J. 1945 The effect of nitrogen fertilization upon the yield and compo- sition of sugarcane. Haw. Plant. Rec. 19. pp. 259-312.

10. Borden, R.J. 1948 Nitrogen effects upon the yield and composition of sugarcane. Haw. Plant. Rec. 52. pp. 1-51.

I 11. Das, U.K. 1936 Nitrogen-nutrition of Sugarcane. Plant Physiol., 11. pp. 251-317.

I 12. Das, U. K. and Cor- 1936 The effect of nitrogen on cane yield and juice q~~ality.

nelison, A. H. Haw. Plant. Rec. 40. pp. 35-36. ,

13. Dillewijn, C. Van 1952 Botany of Sugarcane ; Chapter 12, pp. 196-236. (Th Chronica Botanica Co., Waltl~am, U.S.A.)

14. Du. Toit, J.L. 1954 Sugarcane nutrition in South Africa. Proc. 8 thp Congres of the I.S.S.C.T. Brirish West Indies. pp. 40-44.

15. Evans, H. 1936 Some data on the effect of a heavy dressing of nitrogenou fertilizer o~ the growth and metabolism of sugarcanes Mauritius. Sugarcane Res. Station, Mauritius, Bull. No. p. 9. \

16. Fort, C.A. and 1938 Comparative chemical composition of juices of differen McKaig, N., (Jr.) varieties of Louisiana sugarcane. U.S. Dept. of Agricultur

Tecl; Bull. No. 688. p.68.

17. Halais, P. 1950 Foliar diagnosis, a new guide to fertilization of sugarcane Matxitius. Proc. 7th Congress of the I.S.S.C.T. pp. 218-23

18. Innes, R.F. 1948 Plant analysis in relation to sugarcane nutrition in Jamai Proc. 1948 Meeting of rhe British West Indies Sugar Te Assoc. October '48. pp. 92.

19. lnnes, R.F. 1954 The inorganic fertilizer practices of the principal British Ca bbean sugar-producing territories. Proc. 8th Congress of t I.S.S.C.T. British West Indies, pp. 156-169.

20. Kharin and Smirnova 1936 Original not seen; abstract in Int. Sugar Jour. 38 pp. 447

21. ICobus, J.D. 1900 Original not seen ; quoted from Dillewijn, C. Van, (195 Botany of Sugarcane, Chap. 12. (The Chronica ~ o t a n i Co., Waltham, U.S.A.)

22. Lakshmilcantam, M. 1952 Some practical aspects of application of bulky organic man to sugarcane in Madras. Madras Agic. Jour. 39. pp. 226-2

38. Spencer, G.L. and 1951 pp. 447. Meade, G.P.

39. Yuen, Q.H. and 1937 Borden, R.J.

40. Yuen, Q.H. Borden 1939 K. J. and Hance, F.E.

Unpublished.

Optimum nitrogen requirements of sugarcane in the Ana- kapalle tract. Madras Agric. Jour. 36. pp. 12-22.

Physiological role of nitrogen in growth and metabolism of sugarcane. Proc. Natl. Inst. of Sci. India. 17. pp. 87-98.

Studies in quality of gur. Proc. First Biennnial Conf. Sug. Rrs. Worlcers itz Indian Union, Coinibatore. Part I1 pp. 143-151.

The nitrogen nutrition of sugarcane. Madras Agric. Jour. 39. pp. 243-255.

Manuring of sugarcane. Proc. 19th Ann. Conv. Sugar. T e d . A~soc . of India, Kanpur. Part I . pp. 46-69.

Tissue moisture and its relation to sugarcane ripening. Proc. First Biennial Conf. Sug. Res. Workers in Indian Union, Coitnbatore. Part 11-2. pp. 5-12.

Nitrogenous manuring to sugarcane in Madras (India). Proc. 8th Congress of the I.S.S.C.T., British West Zndies. pp, 144-156.

Soil and Plant Analysis. (The University, Adelaide.)

Fertilizer experiments on sugarcane in India, 1932-39. Misc. Bull. No. 41. Imperial Council of Agricultural Research, India.

Sugarcane Research in the Bombay-Deccan, 1932-44. (Government Press, Bombay.)

'I

Problems of Sugarcane Physiology in the Deccan-canal tract. IV. Mineral nutritioh. B). Nitrogen. Indian J. Agric. Sci., 14. p. 12.

The response of sugarcane to fertilizers. Jour. of Agric. Univ. of' Puerto RiPo. 36. pp. 203-229.

The nitrogen content of sugarcane as influenced by moisture and age. Journal of Apric. Univ. of Puerto Rico. 37. pp. 1-12.

Soil map of the Andhra Slate. Andhra Agric. Jour. 2. pp: 66-75.

Cane-sugar Hand-book. (John Wiley & Sons., New York, U.S.A.)

Chemical analysis of plant as an aid in the control of nitro- gen fertilization. Haw. Plaizt. Rec. 41. pp. 353-383.

Nitrogen in the cane-leaf. Haw. Plant. Rec. 43. pp. 163-207.