Application of extraction with 0.03 M CH 3 COOH as the universal method in orchard soil analysis

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1 Orchard soil analysis 129 FOLIA HORTICULTURAE Ann. 17/2, 05, Application of extraction with 0.03 M CH 3 COOH as the universal method in orchard soil analysis Iwona DomagałaŚwiątkiewicz Department of Soil Cultivation and Fertilization in Horticulture Agricultural University in Kraków 29 Listopada 54, Kraków, Poland iwonadom@ogr.ar.krakow.pl Key words: apple orchards, soil analysis, plant nutrition ABSTRACT Investigations were carried out in in six apple tree orchards localized on the heavy soils. EgnerRiehm s (P and K) and Schachtschabel s (Mg) methods of soil analysis were compared with common extraction with 0.03 M CH 3 COOH (universal method). Significant correlations between the compared methods of analyses were found. The est correlation coefficient was calculated in the case of K (r = 0.83 at significance level 0.05), for P and Mg this values were 0.65 and 0.45, respectively. By using the universal method 44,1% P and 35,4% K (on average) extracted from the soil by calcium lactate (EgnerRiehm method) and 40,3% Mg soluble in Schachtschabel s extract were estimated. According to the obtained results the universal method can be applied for estimation of the nutrient needs of the orchard plants, however, the temporary ranges of soil abundance in the available phosphorus, potassium and magnesium as well as the fertilizer doses proposed for them by Nowosielski (1988) should be verified.

2 130 Iwona DomagałaŚwiątkiewicz INTRODUCTION Fertilizer recommendations for the orchard plants are elaborated on the base of soil analysis, nutrient contents in the leaves and crop estimation (Sadowski et al. 1990, Mika 1998). In the soil only three macronutrients e.g. phosphorus and potassium by the EgnerRiehm method and magnesium by the Schachtchabel method are determined. The optimal ranges in soil test levels the available P, K and Mg for the orchards were presented in Poland for first time by Kłosowski in 1967 and modified in the eighties by Sadowski et al. (1983). The next correction of the fertilization recommendations in 1990 did not change distinctly either the limit numbers or the optimum nutrient rates (Sadowski et al. 1990). The method of EgnerRiehm, applied in the orchard production has been criticized mainly as the laborious one (Ca precipitation before K measurement), limiting the estimation of macronutrients to two only and poorly suitable for the carbonate and organic soil analysis (Trębski et al. 1971, Nowosielski 1988, Bednarek and Lipiński 1995, Komosa and Stafecka 02). On the other hand, many authors emphasize the good correlation of that method with the plant parameters in many pot and field experiments (Fotyma and Fotyma 1995, Fotyma et al. 1996, Gosek 00). In Poland, in the sixties of the twentieth century, Nowosielski and coauthors introduced the common extract for macroelements, sodium, chlorine and boron determination in the soils and substrates. They modified the method of Spurway, by changing the acetate concentration from 0.02 M to 0.03 M and the soil: extractant ratio (1:10) as well as prolonging the extraction time to 30 minutes (Nowosielski et al. 1984). This method, called universal was calibrated and introduced to the fertilization advising system. It has been used until now in soil and horticultural substrate analysis in vegetable, ornamental plant and seed production. The universal method is not applied in the orchard production, however, Nowosielski (1988) fixed the temporary limit numbers of abundance in P, K and Mg for the orchard soils. Possibility of the application of the common method with 0.03 M CH 3 COOH extraction in the orchard soil analysis are reported by Bednarek and Lipiński (1995), Stafecka and Komosa (1998), Komosa (00), Wrona and Sadowski (1998). In Wielkopolska region, Komosa and Stafecka (02) estimated the macro and microelement indices for the orchard soils, analyzed by the universal method. The common extraction methods, including that of 0.03 M CH 3 COOH extraction, allow detecting in one extract many of the nutrients available for plants, to increase the effectiveness of the laboratory work as well as to reduce the costs of analyses. The purpose of the present study was to estimate the usefulness of the universal method and the limit numbers, elaborated by Nowosielski by application of 0.03 M CH 3 COOH in diagnostics of nutrient needs for the orchard plants in comparison with routine methods of soil abundance applied recently.

3 Orchard soil analysis 131 MATERIAL AND METHODS The detailed characteristics of the apple tree orchards, selected for the experiment is presented in Table 1. Investigations were carried out in in the orchards localized on the heavy soils with the 3542% and 3752% of the loam fraction (<0.02 mm) contents in the plough and in the subsoil level, respectively. The ph KCl value in the herbicide strips and in the grass strips was and , respectively. The organic carbon content determined in the soil layer of cm depth was % (Table 2). Table 1. The detailed characteristics of the orchards selected for the experiment Orchard number Cultivar Rootstock Spacing tree (m) 1 Ligol M x Gala P x Jonagold M x Champion M x Elise M x Jonagored M x 3.5 Planting year In the middle of July the leaf and soil samples were taken for analysis, separately from the herbicide strips (HS), grass strips (GS), as well as from the layers of and cm depth. The soil abundance in the nutrients was estimated according to the EgnerRiehm (P and K) and Schachtschabel (Mg) methods and also by the universal method. In the 0.03 M CH 3 COOH extract mineral nitrogen (NNH 4 and NNO 3 ) was measured by the microdestilation method, P was determined by the colorimetric method with vanadium ammonium molibdate, K, Mg and Ca were detected by the atomic absorption spectrometer (Ostrowska et al. 1991). In the soil samples the volume weight as well as the granulometric analysis by the aerometric method of Prószynski (Sady et al. 1994) was determined. The ph in water suspension (ph H2O ) and in 1 M KCl (ph KCl ) at the soil : water (or soil : solution) ratio 1:2 as well as the organic carbon content by Turin s method (Litynski 1976) were measured. The plant material after drying at 70 o C was mineralized in the mixture of acids HNO 3 :HClO 4 :H 2 SO 4. Contents of K, Mg and Ca were detected by the atomic absorption spectrometer, P content was estimated by the blue method with ammonium molybdate. Total nitrogen level was determined by the Kjeldhal method (Ostrowska et al. 1991). The obtained results were statistically verified according to the variance analysis. The investigated factors were soil localization, orchard cultivation system (herbicide/grass strips) and the soil layer depth ( cm or cm). The correlation coefficients were calculated to compare the methods of phosphorus,

4 132 Iwona DomagałaŚwiątkiewicz potassium and magnesium determination as well as those between N, P, K, Mg and Ca contents detected in the leaves of apple trees and their available forms extracted from the soil with calcium lactate and with acetic acid. Table 2. Contents of P and K determined by the EgnerRiehm s metod and Mg by Schachtschabel in the orchard soils Orchard Place Soil layer (cm) 1 HS * GS 2 HS GS 3 HS GS 4 HS GS 5 HS GS 6 HS GS ph KCl C org. (%) P K Mg (mg 100 g 1 ) , LSD 0.05 for: ph KCl C org. P K Mg Orchard Place Soil layer * HS herbicide strip, GS grass strip not significant K/Mg RESULTS AND DISCUSSION EgnerRiehm and Schachtschabel methods Phosphorus content estimated by the EgnerRiehm method in the herbicide strips (HS) layer cm ranged between mg P 100 g 1 and was significantly

5 Orchard soil analysis 133 er than that in cm deep layer ( mg P 100 g 1 ) (Table 2). The similar interdependence was found for samples taken from the two soil levels of the grass strips, which is connected with the so called humus effect, increasing availability of phosphorus. Organic matter affects P mobility by phosphate absorption and, indirectly, by chelating of ions of Ca, Al and Fe, and also by formation of protective layers on the surface of the hydrated iron and aluminum oxides, responsible for P immobilization (Fotyma et al. 1987). According to the statistical analysis the significantly er P content was found in the herbicide strips soils (5.7 mg P 100 g 1 on average) than in the grass strips (4.6 mg P). Considering the soil abundance in P in the HS layer cm, in all 6 orchards the (e.g. er than 4 mg P 100 g 1 ) phosphorus level was found (Table 4). According to the common recommendations, when the phosphorus content in the soil was supplemented before the orchard setting, P fertilization in the fruiting orchard is not applied because of the low mobility of this compound and its poor translocation to the tree rhisosphere (Sadowski et al. 1990). All experiment factors e.g. soil, localization of place and depth of the soil samples significantly affected potassium content detected in the calcium lactate extracts (Table 2). The herbicide strips soils contained mg K 100 g 1 and mg K 100g 1 in cm and in cm layers, respectively. Except for the orchard No 1, potassium content determined in the samples of the grass strips was lower than in those of the herbicide strips, irrespectively of the depth of sample taking. Increase of the nutrients in the soil of the herbicide strips, mainly nitrogen and potassium, resulting from the transfer of the moved grass to the fallow, were reported by Jadczuk (1990) and Wrona and Sadowski (1998). According to estimation of the fertilization needs based on the soil abundance in K in HS layer cm, in three of the investigated orchards (No. 4, 5 and 6) the potassium content, er than 21 mg K 100 g 1 for the heavy soils was found, in two of them the low (lower than 13 mg K 100 g 1, orchards No. 1 and 2) and the one (1321 mg K 100 g 1, orchard No. 3) were observed. The fertilization needs of potassium for the fruiting orchards were on average 801 kg of K 2 O ha 1 in the case of orchards No. 1 and 2, and 5080 kg of K 2 O for the orchard No. 3 (Table 4). Abundance in magnesium, determined in the soil samples, treated with M CaCl 2 and taken from the herbicide strips, ranged from the to level both in the layer cm ( mg Mg 100 g 1 ) and in that cm deep ( mg 100 g 1 ) (Table 2). No significant differences of Mg content between the herbicide strips and grass strips soils were found, however, the er magnesium level in cm layer in comparison with cm one was observed. Only in the case of the orchard No. 2, where the (46 mg Mg 100 g 1 ) Mg content for the heavy soils in cm layer was determined, was the increase of the soil fertility necessary, in the other orchards magnesium content was and exceeded 6 mg Mg 100 g 1 (Table 4).

6 134 Iwona DomagałaŚwiątkiewicz The universal method The way of the soil cultivation in the orchard (herbicide/grass strips) affected distinctly the NNH 4, potassium and calcium concentration in the soil solution, however, did not significantly influence NNO 3 and the available phosphorus and magnesium. The ph H2O as well as P, K, Mg and Ca contents depended on the depth of the soil samples ( cm and cm) (Table 3). The NNO 3 content was affected only by the soil localization (orchard), while the N NH 4 level was related to the place of the sample taking (HS/GS). Significantly more ammonium nitrogen was determined in the soils of the herbicide strips ( mg NNH g 1 ) than of the grass strips (trace to 0.52 mg NNH 4 ). The similar results were obtained by Kozanecka (1995) and Wrona and Sadowski (1998). The total mineral nitrogen in cm layer of the herbicide strips ranged between 0.71 to 2.46 mg 100 g 1 (Table 3). According to Komosa and Stafecka (02) the optimum N min concentration estimated in the 0.03 M CH 3 COOH extract for the orchard soils can be mg NNH 4 + NNO g 1. In investigations of the nutrient nitrogen needs, based on the soil analysis of ammonium and nitrate nitrogen forms, the samples should not be taken both in the intensive dry weather and rainfall conditions. In the orchard production the soil samples are usually taken in the second half of July or at the beginning of August. The longterm dry weather in that time during the experiment years might have affected the obtained results. According to many reports, the soil samples for the mineral nitrogen detection should be taken in the early spring and the mineral nitrogen should be measured in them just after taking from the field (Nowosielski 1974, Fotyma and Fotyma 1995). Similarly, as in the case of the EgnerRiehm method, phosphorus content determined by the universal method was significantly er in the layer cm than in that cm deep, both in the herbicide strips and the grass strips soil (Table 3). According to the estimation of the phosphorus nutrient needs, based of the HS soil analysis in the cm layer, the optimum soil abundance in P was found in orchards No. 1 and 2, the in orchards No. 3, 4, 5, and the low one in orchard No. 6. (Table 4). Nowosielski (1988) reported the nutrient needs of the orchards with the and low phosphorus level as as and 40 kg P ha 1, respectively. According to Komosa and Stafecka (02), the range between mg P 100 g 1 can be used as the optimum for the orchard soils, analyzed by the universal method. In the present experiment only two orchards (No. 1 and 2) were characterized by the available phosphorus content of this range (Table 4). The soil of the herbicide strips contained significantly more potassium, determined by the universal method, in comparison with the grass strips also in the layer cm more potassium was found than in cm one. In the herbicide strips soils mg K 100 g 1 in cm layer were found (Table 3).

7 Orchard soil analysis 135 Table 3. The nutrient contents determined by the universal method in the orchard soils Orchard 1 HS Place GS HS GS HS GS HS GS HS GS HS GS Soil layer (cm) ph H2O EC (ms cm 1 ) N NH LSD 0.05 for: ph H2O EC N NH 4 N NO N NO 3 Σ P K Mg Ca N min (mg 100 g 1 ) Σ P K Mg Ca N min. Orchard Place Soil layer

8 136 Iwona DomagałaŚwiątkiewicz Table 4. Comparison of soil method results for P, K and Mg for herbicide strip in layer cm P K Mg Nutrient Orchard mg dm mg 100 g Universal method Interpretation soil test according to Nowosielski optimal optimal low low low low * value expressed in K, P and Mg ** value expressed in P 2 O 5, K 2 O and MgO Fertilizer recommendations (kg ha 1 *) EgneraRiehma/Schachtschabel methods Fertilizer mg 100 g 1 Interpretation recommendasoil test tions (kg ha 1 **) low low The guide values for K ( mg 100 g 1 ) and Mg ( mg) proposed by Komosa and Stafecka (02) were calculated for the light and soils. These authors report that the test calibration with the very weak extraction solution is universal and irrespective of the soil properties, including soil texture. If the range of potassium content in the present investigations can be assumed as the optimum, only in the case of treatment No. 2 is the increase of the level of this compound necessary (Table 4). According to proposal of Nowosielski (1988) for the heavy soils, in two orchards (No. 1 and 2) the poor potassium content was observed while in four (No. 3, 4, 5 and 6) the one was found (Table 4). The nutrient needs determined by the universal method were 0 and 100 kg K ha 1 for the low and potassium abundance, respectively. The level of magnesium extracted with 0.03 M CH 3 COOH in soil samples of the herbicide strips was low both in cm ( mg Mg 100 g 1 ) and in cm ( mg Mg 100 g 1 ) layers (Table 3). According to Nowosielski (1988) in all six soil treatments fertilization with this compound was necessary at the rate kg Mg ha 1, while according to Komosa and Stafecka (02) only in the orchard No. 6 (Mg content lower than 3.0 mg Mg 100 g 1 ) (Table 4). Calcium level, detected

9 Orchard soil analysis 137 by the universal method ranged between mg 100 g 1 (Table 3). The er Ca concentration was found in the extract of the cm layer than in that of cm one, and in the herbicide strips than in the grass strips. Correlations of the compared methods The significant correlation between the compared methods of analyses was found. The est correlation coefficient was calculated in the case of potassium (r = 0.83 at significance level 0.05; y = x, where y result of detection in 0.03 M CH 3 COOH in mg 100 g 1, x result of detection by Egner Riehm method in mg 100 g 1 ), for phosphorus and magnesium this value was 0.65 (y = x) and 0.45 (y = x) respectively. By the universal method 44.1% P and 35.4% K (on average) extracted from the soil by calcium lactate (EgnerRiehm method) and 40.3% Mg soluble in Schachtschabel s extract were estimated. In the EgnerRiehm method the strong extracting solution, well buffered against H + and Ca +2 concentration, being decisive in the soluble phosphorus forms solubility, extracts partially also the storage forms of it, e.g. P absorbed specifically on the hydrated Al and Fe oxides as well as on calcium carbonate molecules (Egner et al. 1960, Fotyma et al. 1987). In Schaschabel s method extraction is carried out with M CaCl 2, because of the reversibility of exchange between the calcium ions of extractant and Mg ions absorbed, only part of exchanchable magnesium and the whole content of soil solution Mg is determined by this method. The diluted weak organic acid, applied in the universal method, extracts from the soil only easily available for the plants, active forms of nutrients (Nowosielski 1974). Plant nutrition The total nitrogen content determined in the leaves of apple tree grown in the investigated six orchards was ranged between from the low (1.82% N) to the optimum (2.12.4%) (Table 5). In the investigated plant material the optimum phosphorus level was observed ( % P) and the optimum (11.5% K in orchard No. 2) and level of potassium (>1.5% in orchards No. 1, 3, 4, 5 and 6). The est variability was found in the case of magnesium: the deficit content (<0.18% Mg) was estimated in orchards No. 5 and 6, the low in No. 4 and the optimum in No. 1 and 3, while the (>0.32%) level of this element was detected in orchard No. 2. The deficit and low magnesium content found in orchards No. 4, 5 and 6 was probably due to the elevated content of potassium (Table 2). Because of the competition between cations of rhisosphere the potassium concentration in the soil solution can cause insufficient supply of plants in magnesium (Zydlik and Pacholak 1998). Calcium content in the plant material ranged between % Ca, considered as the normal level (Kenworthy, after Sadowski 1967).

10 138 Iwona DomagałaŚwiątkiewicz Table 5. Nutrient contents (% d.m.) in the apple leaves Orchard N P K Mg Ca c 2.48 ab 2.29 a 2.44 ab 2.55 ab 2.60 b 0.21 a 0.26 b 0.19 a 0.26 b 0.22 ab 0.19 a 1.58 a 1.19 d 1.68 ab 1.72 abc 2.06 c 2.01 bc 0.25 bc 0.42 d 0.30 c 0. ab 0.13 a 0.14 a 1.76 b 2.09 c 1.63 b 0.84 a 0.90 a 0.99 a CONCLUSIONS 1. Compared methods of the soil chemical analysis were significantly correlated. 2. By using the universal method 44.1% P and 35.4% K (on average) extracted from the soil by calcium lactate (EgnerRiehm method) and 40.3% Mg soluble in Schachtschabel s extract were estimated. 3. The place (herbicide/grass strips) as well as the depth of the soil samples taking ( cm/ cm) significantly affected the compound content detected by the universal method. In the soil of the herbicide strips er EC, NNH 4, K and Ca contents were found. The cm layer was more abundant in NNO 3, P, K, Mg and Ca. 4. In the leaves of apple trees taken from the investigated orchards the level of potassium, optimum of phosphorus and calcium, deficit to optimum of nitrogen and deficit to of magnesium was found. Only potassium content in the leaves was dependent on K concentration, extracted from the soil both with 0.03 M CH 3 COOH and with calcium lactate. 5. According to the obtained results the universal method can be applied for estimation of the nutrient needs of the orchard plants, however, the temporary ranges of soil abundance in the available phosphorus, potassium and magnesium as well as the fertilizer doses proposed for them by Nowosielski should be verified. REFERENCES BEDNAREK W., LIPIŃSKI W., Rozpuszczalne formy fosforu w glebie poddanej oddziaływaniu następczemu zróŝnicowanego nawoŝenia mineralnego. Zesz. Probl. Post. Nauk. Rol. 421: 15. EGNER H., RIEHM H., DOMINGO W.R., 1960: Untersuchungen veber die chemische bodenanalyse als grundlage fur die bevrteilung des nahrstoffzustandes der boden. II. Chemische extraktionsmetoden zu phosphor und kaliumbestimmung K. Lantbr. Hogsk. Annlr. 26:

11 Orchard soil analysis 139 FOTYMA M., MERCIK ST., FABER A., Chemiczne podstawy Ŝyzności gleby i nawoŝenia. PWRiL, Warszawa. FOTYMA M., FOTYMA E., Współczesne metody badania Ŝyzności gleby i moŝliwości ich wykorzystania w doradztwie nawozowym. Zesz. Probl. Post. Nauk Roln. 421: FOTYMA M., GOSEK S., SZEWCZYK M., Porównanie przydatności róŝnych metod określania odczynu gleby oraz zawartości przyswajalnych form fosforu, potasu i magnezu. Rocz. Gleb. 12: GOSEK S., 00. Ocena metod oznaczania przyswajalnego fosforu w glebie. Fertilizers and fertilization 4(5): JADCZUK E., Transport of mineral elements from grassed alleyways to herbicide strips as a results of grass mowing. Acta Hort. 274: 15. KOMOSA A., 00. In: Nowoczesne diagnozowanie potrzeb nawozowych roślin sadowniczych. VIII Konf. Nauk. Efektywność stosowania nawozów w uprawach ogrodniczych. Warszawa: KOMOSA A., STAFECKA A., 02. Zawartości wskaźnikowe składników pokarmowych dla gleb sadowniczych analizowanych metodą uniwersalną. Roczn. AR w Poznaniu CCCXLI Ogrod. 35: KOZANECKA T., Zawartość mineralnych form NNH 4 i NNO 3 w glebie sadu jabłoniowego. Roczn. Gleb. XLVI 1/2: LITYŃSKI T., JURKOWSKA H., GROCHALA E., Analiza chemiczno rolna. PWN, Warszawa. MIKA A., In: Uwagi o nawoŝeniu sadów. I Ogólnopolskie Sympozjum Mineralnego OdŜywiania Roślin Sadowniczych. Skierniewice: 310. NOWOSIELSKI O., 1974: Metody oznaczania potrzeb nawoŝenia. PWRiL Warszawa. NOWOSIELSKI O., ELLIS E., CZERNIEWSKA W., STRAHL A., TOKARZ A., Common exstraction of trace elements from horticultural soil and substrates. Acta Hort. 145: NOWOSIELSKI O., Zasady opracowywania zaleceń nawozowych w ogrodnictwie. PWRiL, Warszawa. OSTROWSKA A., GAWLIŃSKI S., SZCZUBIAŁKA Z., Metody analizy i oceny właściwości gleb i roślin. Instytut Ochrony Środowiska, Warszawa. SADOWSKI A., Zawartość składników pokarmowych w liściach a wzrost jabłoni. Zesz. Nauk. SGGW, 4: SADOWSKI A., HOŁUBOWICZ T., NURZYŃSKI J., PACHOLAK E., Określenie potrzeb nawoŝenia roślin sadowniczych. Instrukcje upowszechnieniowe. Ser. F, 25: 118. SADOWSKI A., NURZYŃSKI J., PACHOLAK E., SMOLARZ K., Określenie potrzeb nawoŝenia roślin sadowniczych. II. Zasady, liczby graniczne i dawki nawoŝenia. Instrukcja upowszechnieniowa 3, Warszawa: 69.

12 140 Iwona DomagałaŚwiątkiewicz SADY W., DOMAGAŁA I., KOWALSKA I., LIS KRZYŚCIN A., OSTROWSKA J., Przewodnik do ćwiczeń z uprawy roli i nawoŝenia roślin ogrodniczych. AR Kraków. STAFECKA A., KOMOSA A., Wspólny wyciąg do analizy gleb sadowniczych. I Ogólnopolskie sympozjum mineralnego odŝywiania roślin sadowniczych, Skierniewice: TRĘBSKI L., SORCZYŃSKI W., SZOT A., WITKOWSKA H., Wstępne badania nad przydatnością metod: EgneraRiehma, Gohlera oraz zmodyfikowanej metody Spurwaya do ustalenia potrzeb nawoŝenia roślin warzywnych. Pamiętnik Puławski 50: WRONA D., SADOWSKI A., In: Efekty nawoŝenia jabłoni azotem w pierwszych czterech latach po posadzeniu. I Ogólnopolskie sympozjum mineralnego odŝywiania roślin sadowniczych. Skierniewice: ZYDLIK Z., PACHOLAK E., In: Wpływ wieloletniego zróŝnicowanego nawoŝenia N, P, K i Mg na wzrost i plonowanie jabłoni odmiany Cortland oraz zawartość składników w glebie i liściach. I Ogólnopolskie sympozjum mineralnego odŝywiania roślin sadowniczych. Skierniewice: ZASTOSOWANIE METODY WSPÓLNEJ EKSTRAKCJI Z 0,03 M CH 2 COOH W ANALIZIE GLEB W SADOWNICTWIE Streszczenie: Badania prowadzono w latach w sześciu sadach jabłoniowych załoŝonych na glebach cięŝkich. Ocenę zasobności gleb w składniki pokarmowe prowadzono metodą EgneraRiehma (P i K) i Schachtschabela (Mg) oraz z wykorzystaniem testu uniwersalnego z ekstrakcją 0,03 M CH 3 COOH. Wartość współczynników korelacji była najwyŝsza dla potasu (r = 0,83, istotne dla p = 0,05), a dla fosforu i magnezu wynosiła odpowiednio r = 0,65 i r = 0,45. Wykazano istotną korelację pomiędzy porównywanymi metodami analiz gleby. Metodą uniwersalną oznaczano średnio 44,1% P i 35,4% K ekstrahowanego z gleby mleczanem wapnia (metoda EgneraRiehma) oraz 40,3% Mg przechodzącego do wyciągu Schachtschabela. Uzyskane wyniki badań wskazują, Ŝe metoda uniwersalna moŝe być stosowana do oceny potrzeb nawoŝenia roślin sadowniczych, ale uściślenia wymagają tymczasowe przedziały zasobności w przyswajalny fosfor, potas i magnez oraz dawki nawozów zaproponowane dla tych przedziałów przez Nowosielskiego (1988). Received April 24, 05, accepted November, 05