Effects of organic matter and controlled-release fertilizer on nutrient retention during intermittentmist propagation

Scientia Horticulturae, 8 (1978) 155--162 Elsevier Scientific Publishing Company, Amsterdam -- Printed in The Netherlands

155

EFFECTS OF ORGANIC MATTER AND CONTROLLED-RELEASE FERTILIZER ON NUTRIENT RETENTION DURING INTERMITTENTMIST PROPAGATION

D.F. HAMILTON' and C.R. JOHNSON IFAS, Department of Ornamental Horticulture, University of Florida, Gainesville, FL. (U.S.A.) 1 Present address: Department of Horticulture, Purdue University, West Lafayette, Indiana 47907 (U.S.A.) Florida Agricultural Experiment Stations Journal Series Number 214. (Received 19 August 1977)

ABSTRACT Hamilton, D.F. and Johnson, C.R., 1978. Effects of organic matter and controlled-release fertilizer on nutrient retention during intermittent-mist propagation. Scientia Hortic., 8: 155--162. Semi-hardwood cuttings of Ligustrum japonicum Thunb. and Juniperus conferta Pail. were propagated in sand or sand : peat (1 : 1 v/v) and top-dressed with osmocote controlled-release fertilizers at various rates. Soluble salts, NO3-, P and K leaching through media was greater in sand, especially with osmocote 14--14--14. Loss of P and K in both media was not as rapid as the loss of NO~-. The pH of leachate from sand : peat was significantly less than that from sand. The 18--6--12 osmocote provided steady nutrient release in both media.

INTRODUCTION Leaching-losses f r o m liquid fertilization, n u t r i e n t m i s t , a n d d r y fertilizat i o n are o f t e n high. Waters ( 1 9 6 0 ) f o u n d t h a t t h e leaching-losses f r o m surface a p p l i c a t i o n versus i n c o r p o r a t i o n o f a d r y fertilizer w e r e h i g h e s t f r o m inc o r p o r a t i o n , w i t h t h e h i g h e s t loss in t h e first 1A--1A i n c h o f l e a c h a t e . L e a c h i n g is o f t e n r e l a t e d t o e f f e c t i v e n e s s o f m e d i a c a t i o n e x c h a n g e c a p a c i t i e s in ret a i n i n g n u t r i e n t s in t h e m e d i u m f o r p l a n t u p t a k e . C o n o v e r a n d J o i n e r ( 1 9 6 3 ) o b t a i n e d t h e b e s t r o o t i n g - p e r c e n t a g e a n d q u a l i t y o f P i t t osporum tobira ( T h u n b ) Ait. w i t h p e a t : p e r l i t e (1 : 1 v/v). S o k r a t o v a ( 1 9 6 5 ) r e c o r d e d aerat i o n a n d p e r m e a b i l i t y o f p e a t a l o n e a n d in c o m b i n a t i o n w i t h s a n d a n d perlite, a n d f o u n d p e a t : s a n d (1 : 1 v/v) a n d p e a t : p e r l i t e (1 : 1 v/v) e q u a l l y satisfactory for root growth and development. Our study was designed to determine the leachability of certain nutrient salts f r o m c o n t r o l l e d - r e l e a s e fertilizer a d d i t i o n s t o s a n d : p e a t c o m b i n a t i o n s

156 used as propagating-media for Ligustrum japonicum and Juniperus conferta cuttings during a 12-week propagation period. MATERIALS AND METHODS Semi-hardwood tip cuttings (25 cm long) o f Ligustrum japonicum, and Juniperus conferta were taken on 3 April 1975 from stock plants growing in full sun. Cuttings were dipped in a 0.5% indolebutyric acid (IBA) talc prior to sticking and were placed under intermittent mist which delivered 5.0 liters water/0.093 m 2 o f surface weekly. Two propagating-media: medium grade sand and sand : canadian peat (1 : 1 v/v), were compared. Media were amended with Perk (fritted micronutrient mixture manufactured b y Kerr McGee, Jacksonville, Florida, U.S.A,) at 1.5 kg per m 3 media. Media were thoroughly wetted before applying fertilizer treatments and sticking cuttings. Immediately after sticking cuttings, media were top-dressed with osmocote (donated b y Sierra Chemical Co., California, U.S.A.; the 14--14--14 releases for 3--4 months and 18--6--12 releases for 8--9 months according to manufacturer's specifications) 14--14-14 at 0, 9.6 and 19.2 g/0.093 m 2 o f medium or o s m o c o t e 18--6--12 at 0, 7.5 and 15.0 g/0.093 m 2 of medium. The experiment was a 2 × 5 factorial, comparing media and fertilizer treatments for each plant material. A randomized complete blocks design was used with 5 replications per treatment and 20 cuttings per replication. Leachate through media from each treatment was collected weekly and soluble salts and pH recorded. Nitrate (NO~), potassium (K) and phosphorus (P) levels were determined bi-weekly. Nitrate determinations were made with a specific-ion electrode. K levels were determined using a Beckman flame emission s p e c t r o p h o t o m e t e r and P levels were determined with a Perkin-Elmer atomic absorption spectrophotometer. RESULTS AND DISCUSSION

Soluble salts. -- The level of soluble salts in the leachate varied with b o t h fertilizer treatment and propagating-medium. There was a rapid loss o f nutrients from media with misting, especially with o s m o c o t e 14--14--14 (Table 1). Dry weights and tissue analyses showed that nutrients were n o t utilized b y plants. This is probably due to an early and rapid release o f nutrients before root initials had elongated. Soluble salts leached from the sand treated with o s m o c o t e 14--14--14 were consistently more than from sand/peat (Table 1). There appeared to be a greater retention of nutrients in the medium containing organic matter. These differences were also apparent when using 18--6--12, b u t only during the last half o f the experiment. It is accepted that the level o f soluble salts in a medium depends n o t only on water-holding capacity, b u t also on the cati0n-exchange capacity (CEC) of that medium (Tisdale and Nelson, 1975).

157

TABLE 1 Effect of propagating-medium and osmocote controlled-release fertlizers on soluble salts in leachate through the medium. Numbers within a column not followed by the same letters are significantly different at the 1% level. Rates of osmocote controlled-release fertilizer ("treatment") are expressed in g]0.093 m: of each medium. Treatment

Soluble salts (millimhos/cm) Weeks after sticking cuttings 2

4

6

8

10

Sand 18--6--12 at 7.5 g 18--6--12 at 15.0 g 14--14--14 at 9.6 g 14--14--14 at 19.2 g No fertilizer

0.368 0.358 0.402 0.452 0.354

c c b a c

0.398 0.502 0.490 0.628 0.430

c b b a bc

0.392 0.430 0.536 0.802 0.440

c c b a c

0.414 0.622 0.478 0.542 0.410

b a b a b

0.378 0.496 0.512 0.394 0.386

b a a b b

Sand/peat (1 : 1 vlv) 18--6--12 at 7.5 g 18--6--12 at 15.0 g 14--14--14 at 9.6 g 14--14--14 at 19.2 g No fertilizer

0.336 0.362 0.356 0.340 0.356

c c c c c

0.332 0.512 0.398 0.372 0.392

c b c c c

0.278 0.358 0.362 0.518 0.266

d c c b de

0.314 0.334 0.364 0.398 0.324

c c c bc c

0.312 0.342 0.268 0.298 0.366

bc bc c c b

T h e h i g h e r t h e CEC o f t h e m e d i u m , t h e m o r e f e r t i l i z e r t h a t c a n b e a p p l i e d w i t h o u t r a d i c a l l y a f f e c t i n g s o l u b l e s a l t levels. H o w e v e r , i t s h o u l d n o t l e a d t o t h e false a s s u m p t i o n t h a t a m e d i u m c o n t a i n i n g l o t s o f p e a t will n o t h a v e s o l u b l e - s a l t p r o b l e m s . A s a n d / p e a t m i x c a n have a h i g h e r s o l u b l e - s a l t c o n t e n t t h a n s a n d b e c a u s e s a n d / p e a t l e a c h e s less, a n d salts a c c u m u l a t e b e c a u s e o f h i g h m o i s t u r e levels a n d a high CEC. pH. -- The pH of leachate was significantly lower f r o m s a n d / p e a t than s a n d a f t e r t h e t h i r d w e e k ( F i g . 1). C a n a d i a n p e a t n o r m a l l y h a s a p H o f 3.5 - - 4. 5 a n d a s a n d / p e a t m i x w o u l d b e e x p e c t e d t o l o w e r p H o f l e a c h a t e m o r e than sand. However, based on these results the pH was n o t m o d e r a t e d b y t h e a d d i t i o n o f s a n d . T h i s c o u l d be a p r o b l e m in p r o p a g a t i o n , as m a n y p l a n t s are s e n s i t i v e t o m e d i a p H e v e n d u r i n g r o o t i n g . T h e r e was n o v a r i a t i o n in p H o f l e a c h a t e d u e t o f e r t i l i z e r t r e a t m e n t . The decreased pH with additions of organic m a t t e r could have affected leaching of certain nutrient elements from the medium. Contrary to cation e x c h a n g e , t h e c a p a c i t y f o r r e t a i n i n g a n i o n s i n c r e a s e s w i t h a d e c r e a s e in p H o f w a t e r in t h e r o o t - m e d i u m e n v i r o n m e n t . W i t h t h e e x c e p t i o n o f p h o s p h a t e s (PO4-), a n d t o a l e s s e r d e g r e e s u l f a t e s (SO4-), a n i o n s s u c h as n i t r a t e s (NO3-) are l a r g e l y l o s t f r o m m i x e s b y l e a c h i n g . A s a n i o n e x c h a n g e is l a r g e l y a p H d e p e n d e n t f u n c t i o n , t h e m o r e a c i d t h e w a t e r in t h e soil s o l u t i o n , t h e g r e a t e r

158

Propagating medium I O-~OSand LSD 0.01 ~-~Sand:Peat (I:I v/v)

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159

the absorption of PO4- and NO3-. In an attempt to determine if this did occur the quantities o f certain nutrients contained in the leachate were determined. Nitrates. - - Leaching through sand was significantly greater only from the fourth to the eighth week (Fig. 2). This supports earlier findings that the decrease in pH resulting from the organic matter would increase anion absorption (NO3-) by the propagating-medium. For newly-rooting cuttings this could be quite important. More available NO3- in a medium as root initials develop could result in faster growth rate o f cuttings immediately after rooting. It is apparent that much of the nitrogen from o s m o c o t e 1 4 - - 1 4 - - 1 4 is lost very soon after sticking o f cuttings (Fig. 3). This means a loss o f nitrogen, es-

80

Rate per 0.093 m2

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Fig. 3. Effect o f osmoeote controlled-release fertilizer on nitrate ( N O ; ) levels o f leachate. Fig. 2. Effect o f organic matter in the propagating-medium on nitrate levels in the leachate.

160

pecially for slower-rooting species o f plants. On the other hand, 15.0 grams osmocote 18--6--12 showed a slower rate o f nitrogen release. Phosphorus and potassium. -- All osmocote treatments, except the low rate of 18--6--12, resulted in significantly more P and K in the leachate during the first m o n t h after sticking cuttings (Figs. 4 and 5). As with NO3- accumulation, the greatest a m o u n t of P and K leaching occurred with 14--14--14 at 19.2 g followed by 14--14--14 at 9.6 g and then 18--6--12 at 15.0 g. However, unlike NO3- accumulation, P and K leaching was found to be greater with high rates of osmocote than in non-fertilized controls. These results indicate that P and K do n o t leach as readily as NO3- in these media. There were no significant differences in amounts o f either P or K in leachate as a result o f organic m a t t e r in the propagating-medium.

Rate per 0.093 m2 8

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WEEKS AFTER STICKING CUTTINGS

Fig. 4. Effect o f osmoeote controUed-rele~mefertilizer on phosphorus (P) levels in leachate.

161

Rate per 0.093 m2

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9.6gI~-14-14 19.2 g14-14-14

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WEEKS AFTER STICKING CUTTINGS

Fig. 5. Effect o f osmocote controlled-release fertilizer on potassium (K) levels in leachate,

CONCLUSION

Controlled-release materials with a rapid rate o f release such as osmocote 14--14--14 appear useful in propagation only in heavier mixes. Without organic matter, most of the nutrients supplied by 14--14--14 rapidly leach through the medium. Osmocote 18--6--12 at 15.0 g/0.093 m 2 was found to maintain a steady state o f release under our experimental conditions. This would presumably ensure continuous availability o f N, P and K with increasing plant needs. Our results also emphasize that efficiency o f a production system varies with cultural practices. Careful regulation o f fertilizers, media, etc. could decrease wastefulness o f nutrients and increase production efficiency.

162

REFERENCES Conover, C.A. and Joiner, J.N., 1963. Rooting response of Pittosporum tobira 'variegaturn' as affected by 3-indolebutyric acid, rooting media and age of wood. Proc. Fla. State Hortic. Soc., 76: 480--483. Sokratova, E.G., 1965. The water permeability and aeration of substrates for rooting soft. wood cuttings under artificial mist. Dokl., Mosk. Skh. No. III (part II): 45--52. Tisdale, S.L. and Nelson, W.L., 1975. Soil Fertility and Fertilizers. Macmillan, New York. Waters, W.E., 1960. The effects of potassium source and soil mixtures on leaching of fertilizer salts from clay pots. Proc. Fla. State Hortic. Soc., 73: 384--389.