TECHNICAL BULLETIN 99 ISSN 0070-2315

NITROGEN AND PHOSPHORUS FERTILIZING OF CARROTS

P.I. Orphanos and V. D. Krentos

AGRICULTURAL RESEARCH INSTITUTE MINISTRY OF AGRICULTURE AND NATURAL RESOURCES NITROGEN AND PHOSPHORUS FERTILIZING OF CARROTS

P.I. Orphanos and V. D. Krentos

SUMMARY

Carrots have been an important export crop since the mid 1950s but the course of theindustly in production, price of the produce and exports has been rather enatic. The crop is sown in November and harvested in April through June. Before 1974 carrot growing was concentrated in the --Zodhia area. The eight experiments reported here were carried out in this area over the period 1968-71, and tested the combinations of four rates of N (0.63, 126. and 189 kgha) and four rates of P (0.23,46,and 69 kgiha). As a result of previous fertilizer P application. all experimental soils but one tested more than 8 ppm Olsen P. The test variety was Chantenay but in the last experiment Nantes was also included. In sir out of the eight experiments N increased yield significantly, and 63 to 1'26 kg Niha was required for maximum yield. By contrast only in one experiment in which the soil tested a mere 1 ppm Olsen P was yield increased by fertilizer P up to the rate of 46 kg Piha. The increase in yield due to N application was accompanied by a coincident increase in the percentage of exportable yield but at the highest N rate (189 kg Nha) percent exportable yield slightly declined. The dry matter content and the N,P and K contents of the roots were not influenced by either N or P fertilizing. With sufficient N and P fertilizing exportable yield in these experiments was around 70 tiha, which is appreciably higher than the presently obtained commercial yields. Therefore, the optimum rates determined in the present experiments are still valid. Thc N rate should be in the range 60 to 125 kdha, and should preferably be applied.. in two doses. one at sowing and the other in March. In soils testingless than 10ppm Olsen P. 46 kg Plha should be applied; in soils ke testine between 10 and 20 .ovm . Pa maintenance dose of 20 Plha should he aoolied... , but in soils testine mare than 20 ppm I? fertilizer P need not be applied.

An6 ro 1956 ia raporra ~ivarpra oqpavrtxj ESaywyl~j~aXhrdpyzla ./la iqv Kvnpo p~ pcyakg dpwg Slunupavo~tgr6oo urn ouvoh~rjnapayoyj Fa! rtg &\aywyig 650 xar air< rtpdg. H onopa yiv~ratrarci rov Noip6p~o-A~~dpRp10ral q oujicopr6fl mi6 rqv rrspio6o Anplbiou-Iouviou. nptv ra 1974 ra xup6rra ~a~~,&pyo6vm\~KUpiogorq n&plo%fl Apyariou-Kurw~ontag-Zrjhlaq. Taoxri, nclpapuru nou n&p~ypd$ovrato' aurfl rq Gqpoai~uoq$:IIVUV o~qv nep~oxij UUT~ ra~a ~qv n~pioSo 1968-71. Aon~pdoiqxav01 nuv6uaopoi reootpwv 6n~ntSovu:r(lroulO. 63.126 Kal189 kslha) Kat reooapov E~~TT~~~UV,@~~+O~OU(~,23,46 KUL69 kdh;~) To t6a+og rov natpupur~rujva~poiv. pi rqv c5aipaoq EVO~nept~ixc nep~aoor~po and 8 ppm Olsen P hoyw rrpoqyoupivov hlndvoeov p& +oo+6po. H not~thiunou xpqoiponolj@ql(~jrav q Chantenay ahha oro IE~.EUTU~~rsipupu ~pqo~ponotijBq~eua1 q nol~lhiaNantes. Xe 65, an6 ru 0x16 nstpapara ro ~

Carrots (Daucus carota) have been an Eight experiments were carried out in the important export crop since the mid 1950s, but Argaki-Katokopia area over the period 1968-1971. annual production, exports and prices have been The top 60 cm soil layer of the experimental fields fluctuating wildly through the years (Table 1); was medium to fine textbred, low in organic 1963 was the year of record exports (28 670 tons). matter, and mostly decalcified (Table 2). The In the period 1980-6 exports ranged between 4 340 fields were selected on the basis of available soil P tons (in 1985) and 7 740 tons (in 1981). Production (Olsen P), but because of past liberal applications per hectare has increased steadily, particularly of P fertilizers the soil of only one of them after 1974. One of the factors contributing to such contained less than 8 ppm P (Table 3). As in all increased yield has been the use of permanent low- Cypriot soils, except those in the igneousTroodos angle and low-capacity sprinklers, which enable area, exchangeable K was higher than 250 ppm timely and uniform irrigation, and reduce the (Table 3), the highest values indicating past incidence of 'green shoulder'. applications of farmyard manure.

The experiments reported here were camed out The experiments were factorial and tested the over the period 1968-71 in the Argaki-Katokopia combinations of four N rates, i.e. 0, 63, 126 and area, which was then the main carrot growing area. 189 kg Nlha, and four P rates, i.e. 0,23,46 and 69 Since these experiments were imgated by kg Ptha. There were four replications in a sprinklers and' the yields obtained were randomized complete block design. The appreciably higher than the present average fertilizers, i.e. ammonium sulphate and single commercial yield, the results are still valid, and superphosphate (triple superphosphate in the belated publication is warranted. 1970-1 experiment), were applied broadcast and then rotavated into the soil prior to sowiitg in mid November. Plot size was 2.3 x 9.2 m of which only the cential 0.9 x 6.1 m area was recorded. The variety Chantenay was used but in the last experiment (Katokopia E, 1970-1) the variety Nantes was also included.

Table 1. Carrot production and exports in selected years high- lighting the cource of the idustry over the period 1956- The crop was sown in late November by machine 1986 (source: Carrot Marketing Board). in rows spaced 10 cm apart, and the seed rate was 5 kglha. Irrigation was by sprinklers and the total amount of water applied ranged between 185 and Grower's average 280 mm. Linuron was spray-applied one week Area Yield Exports price after sowing to control the weeds. In certain cases Year (ha) (tonsha) (tons) (centslkg) mineral oil was sprayed after the crop had emerged to control wild oats. Occasionally, the plots were 1956 384 13.4 2 8M) additionally weeded by hand. 1960 441 26.1 10 430 1963 1 338 23.9 28 670 1965 468 29.9 10960 At harvest, in early to mid May (about 160 days 1969 765 31.4 20 470 3.4 from sowing), the roots were graded into 1974 565 24.8 12 560 2.6 exportable and non-exportable, the latter 1975 87 31 6 2 500 9.0 comprising roots less than 15 mm in diameter or 1977 334 34.4 10 000 6.3 misshapen. The dry matter and N, and 1980 174 40.2 6 330 6.9 P, K 1983 156 39.7 4 530 11.0 contents of the,roots were determined in one 1986 134 47.0 5 110 7.0 replication of each of the three experiments of 1968-9. Table 2. Particle-size distribution and organic matter and CaC03 contents of the soil profile of representative experimental sites.

Experiment Organic Year Location Depth Clay Silt Sand matter CaCOl

cm 1968-9 Argaki A 0-30 30-60 1969-70 Argaki B 0-30 30-60 Argaki C 0-30 30-60 KatokopiaC 0-30 30-60 Katokopia D 0-30 30-60

Table 3. Bicarbonate-extractable P (Olsen P) and exchangeable K in the plough layer of the experimental fields.

RESULTS AND DISCUSSION Experiment OlsenP Exchangeable K Year Location (PPm) (PP~) With the exception of Argaki B and Katokopia D experiments, N application increased yield 1968-9 Argaki A 1 300 (Table 4 , Fig. 1). By contrast, P application Katoko~iaA .8 450 markedly increased yield in only one experiment (Argaki A), the soil of which contained only 1 ppm 1969-70 Argaki B 27 500 P (Table 3), and slightly increased yield only of Argaki C 8 590 Nantes carrots in another experiment (Katokopia Katokopia C 12 420 E), the soil of which contained 9 ppm P. In no case Katokopia D 20 350 was there a significant NxP interaction (Table 4). The N requirement was between 63 and 126 kglha 1970-1 Kalokopia E 9 270 and the P requirement 46 kg/ha in the only case where the soil contained less than 8 ppm P. Table 4. Statistical significance of the responses of exportable yield of Chantenay carrots to N and P The increase in exportable yield due to N (also of Nantes carrots in 1970-1). application was accompanied by a coincident increase in the percentage of exportable yield but Experiment at the highest N rate (189 kg/ha) percent Year Location N P NxP exportable yield slightly declined (Table 5). 1968-9 Argaki A *a ** NS Similarly, in the single case (Argaki A) in which Katokopia A ** NS NS .* soil P was deficient, P application increased the Katokopia B NS NS percentage of exportable roots, but in the other 1969-70 Argaki B NS NS NS experiments the percentage of exportable roots ArgakiC NS NS was not influenced by P application. Because Katokopia C *a NS NS *irrigationwas by sprinklers, the incidence of 'green Katokopia D NS NS NS shoulder' was limited. 1970-1 KatokopiaE Chantenay ** NS NS The percentage of root dry matter and its N, P Nantes - *a * * NS and K contents were determined in only one 1.1; I Th~.vt~~~.T~.~tiY d~~.ll~f~r~~l~~.~~~~~~nc~p~~~~:~l~lc~~cld~~f~'lt~~~l~~~~~~ ;.!rrt,l\,~t k.s~.A,>p~~I.. ,,Is

t~f\:tlllc\ tl,r krn III,L, ll,1r\ ~nd~catc5". LSD fur compxrlng h~nhti 3nJ t' I~C.IRI replication of each of the three experiments of commercial yield, the optimal N rate found in 1968-9 (Tables 6 and 7). Therefore, only the means these experiments, i.e. 63-126 kg Nha, is still of the treatments over the three experiments ipplicable. The exact rate to be applied will (considered as replicates) can be statistically depend on the fertilizer practices with the crops compared. Such comparison showed that dry preceding the carrots. Since the presence of excess matter content was not significantly influenced N, particularly when the roots are about 6 mm in either by N or by P application. diameter, may cause splitting (Bienz, 1965) and rough skin, it would perhaps be better if the N were Concentration of N in root dry matter increased given in two split doses, one at sowing and the significantly when N was applied in excess of 126 other in March. kg Nha (Table 7). However, even such increased values were much lower than values reported by With regard to phosphorus, the present results Haworth et al. (1966) for English carrots. confirm the generally held view that 10 ppm Olsen Concentration of P slightly increased with P P in the plough layer is sufficient for maximum application, but concentration of K was not yields of most crops. This has been additionally influenced by either N or P application. confirmed with potatoes (Krentos and Orphanos, From the data of the present experiments it can 1979a), and wheat and barley (Krentos and be calculated that a yield of 60 tlha roots (9.5% dry Orphanos, 1979b). However, it is suggested that matter contaming 0.9% N, 0.2% P and 3.0% K) for soil P values less than 10 ppm 46 kg Plha should be applied, and for values between 10 and 20 ppm removes 49 kg N, 11 kg P and 162 kg K per hectare. a maintenance dose of 20 kg Plha should be Since the yields obtained in these experiments applied. For values higher than 20 ppm no P should were markedly higher than the current average be applied.

Table 5. Percent exportable roots as influenced by N and P fertilizing.

Experiment N P (kgiha)

Year Locat~on 0 63 126 189, 5' 0 23 46 69 '

1%8-9 Argaki A 65.7 76.2 75.0 77.7 6.69 46.3 73.0 79.4 79.2 KatokopiaA 70.0 79.6 80.0 76.3 4.29 77.5 .76.7 79.1 75.6 KatokopiaB 47.9 66.8 71.6 75.2 9.70 65.6 69.8 68.5 70.6

'1969-70 ArgakiB $0.9 89.8 86.7 87.5 2.16 89.3 87.7 87.9 89.9 Argaki C 85.0 81.0 80.2 75.7 5.82 81.4 81.6 76.5 81.8 KatokopiaC 90.7 93.4 92.4 92.9 2.37 91.7 92.0 93.6 92.9 KatokopiaD 81.7 77.2 76.9 76.2 6.05 79.5 79.5 79.2 74.1

1970-1 KatokopiaE Chantcnay 86.5 85.4 82.1 78.8 4.45 86.0 83.6'80.9 82.7 Nantes 80.9 84.3 81.9 81.8 3.99 83.5 80.6 83.6 81.8

* for comparing both N and P means Table 6. Percent dry matter in carrot roots as influenced by N and P fertilizing.

Experiment Nitrogen (kglha) Phosphorus (kgiha)

Year Location 0 63 126 189 LSD,5' 0 23' 46 69

1968-9 Argaki A 9.91 9.61 9.74 9.29 10.08 9.37 9.58 9.53 KatokopiaA 9.17 9.59 8.64 8.54 9.18 8.55 8.99 9.22 KatokopiaB 8.10 9.66 8.87 8.18 9.14 8.84 8.14 8.69 Mean 9.06 9.66 9.08 8.67 0.59 9.47 8.92 8.90 9.15

* for comparing both N and P means

Table 7. Concentration of N, P and K in carrot root dry matter as influenced by N fertilizing (data from one replicate of each experiment).

Nitrogen (kgiha) Phosphorus (kgiha)

Experiment 0 63 126 189 0 3 46 69 LSD*

%Nitrogen Argaki A Katokopia A Katokopia B Mean

%Phosphorus Argaki A Katokopia A Katokopia B Mean

%Potassium Argaki A Katokopia A Katokopia B Mean

* for comparing both N and P means ACKNOWLEDGEMENTS Haworth, F.. Cleaver T.J., and J.M.Bray. 1966. The eflectsof different manurial treatments on the yicld and mineral composition of carrots. Journal of We thank G. Roushias, A. Minas. C. HorricuIruralScience 41:299-310. Hadjiloucas and Chr. Xylaris for technical assistance. and Maria Pitri for assistance with the Krentos. V.D.. and P.I. Orphanos. 1979a. Nitrogen, processing of the data. phosphorus and potassium fertilizers for potatoes in . Journal of Apricultun~lSc;ence, Cambridge REFERENCES 92:645-661

Bienz. D. R. 1965. Carrot splitting and second growth in Central Washington asinfluenced by spacing, timcof Krcntos, V.D.. and P.I. Orphanos. 1979h. Nitrogen anrl sidedrcssing and other cultural practices. phosphorus fertilizers for wheat and barley in a semi- Proceedings of the American Socier?. for arid region. Journal of Agricoltoral Science, Horriculrural Sciencc 86:406-410. Carnbridpe93:711-717.

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