Abstract: A field study was carried out to evaluate the nutrient status of apple orchards in forty one commercial farms in Gharbia, as alluvial soils and Menofiya, as newly reclaimed soils, governorates, Egypt. The use of leaf and soil analysis is an important tool for monitoring plant nutritional status. Results revealed that the nutrients shortage of these soils mostly cases related to their alkalinity, clay content, low organic matter. Iron may be a limiting factor of apple growth at both locations. It is of interest to note also that the correlation of soil properties and its nutrient concentration, with leaf nutrients content indicated the occurrence of imbalanced nutrition. The obtained results will be used as a basis for subsequent experimental fertilizer treatments. This will lead to determine the most suitable fertilization policy for improving crop yield of apple and quality to maintain soil fertility and to reduce environmental pollution.
Introduction
Anna is a newly established apple cultivated in Egypt. In order to obtain maximum productivity from a given cultivated area, it is necessary to evaluate the nutritional requirements for apple grown in it as well as to determine the availability of nutrients in the soil in order to apply a balanced fertilizing program.
The concentrations of mineral nutrients in the soil solution, i.e., the available nutrient concentration varies widely, depending on many factors such as soil pH, soil organic matter content and fertilizer application (Marschner, 1986).
In high pH soils, it is known that micro nutrients as well as some macro-nutrients may be limiting (Miller et al., 1998).
Application of N and P fertilizers, without K or micro nutrients can be a reason for imbalanced nutrition of trees (Saurate, 1987 and Fawzi, 1992). The major limiting elements differ from crop to crop and from one location to an other for the same crop (El-Fouly, 1984).
The purpose of the following investigation was therefore to evaluate the nutritional status of apple trees under two different conditions to increase yield and improve fruit quality.
Materials and Methods
A survey study was carried out in 2001 season on Anna apple grown in orchards located at Tanta, as alluvial soils, Gharbia governorate (30 orchards) and Sadat City, as a newly reclaimed soil, Menofiya governorate (11 orchards), Egypt.
Trees were 8-12 years old. A representative soil samples from the surface layer of every orchard (0-40 cm) were taken before fertilizers application. All the orchards received available amount of fertilizers depending on farmer practices for each farm (Table 1).
| Table 1: | Farmer’s practices in Gharbia and Menofiya governorates, Egypt |
Samples of leaves were taken in middle growth season at random from each orchard to determine nutrient concentration according to Chapman and Pratt (1978).
The values are evaluated according to Ankerman and Larg (1974). Correlations between soil characters and leaf nutrient concentration were computed using COSTAT statistical program.
Results and Discussion
Soil characterization and nutritional status: Data in Table 1 show that apple trees were fertilized with low amounts of farmyard manure, higher amounts of N and P than recommended, once and without either K or micro nutrients fertilizers were added.
The soil reaction was highly alkaline, in the same time the organic matter content of almost all samples were low (below 2%) (Table 2). In this respect, Sillanpää (1982) reported that low organic matter content associated with high pH cause the reduction in most micro nutrients availability.
Analytical data of soil samples in Table 2 indicated that soils of most samples contained CaCO3 levels lower than 4% which considered low and thus has no effect on nutrient availability.
The tested soils varied with respect to their texture from sandy clay loam in Gharbia to loamy sand in Menofiya. The importance of such variation resides in the well known relationship between soil texture and soil reserve of the various nutrients (El-Damaty et al., 1973). Decrease in amount of available nutrients in Gharbia G., most probably due to high clay content which inhibit the root growth. Similar result was previously obtained by Torbert and Wood (1992).
| Table 2: | Soil physico-chemical characteristics of apple trees in Gharbia and Menofiya governorates. |
| L : Low M : Medium H : High VH : Very High | |
| Table 3: | Nutrients concentration of apple leaves in Gharbia and Menofiya governorates |
| L : Low M : Medium H : High VH : Very High | |
| Table 4: | Correlation coefficient between soil characteristics (0-40cm depth ) and leaf nutrient concentrations, in the surveyed apple orchards of Gharbia governorate |
| NS: Non significant*, **, Significant at 0.05 and 0.01 probability levels, respectively. r 0.05 = 0.361r 0.01 = 0.463 | |
| Table 5: | Correlation coefficient between soil characteristics (0-40cm depth) and leaf nutrient concentrations, in the surveyed apple orchards of Sadat City in Menofiya governorate. |
| NS : Non significant*, **, Significant at the 0.05, 0.01 probability levels, respectively. r 0.05 = 0.602r 0.01 = 0.735 | |
On the other hand, shortage of nutrient availability of Sadat City soil, Menofiya G. may be attributed to high sand percentage (loamy sand texture) and its poverty in available nutrients. Similar results were reported by Abdel-Salam et al. (1974). It is also possible to observe that nitrogen in both locations ranged between medium in the former to low in the latter location. High clay content of the former location probably led to more potassium and phosphorus fixation by clay minerals and thus, reduction in their availability. The same results reported by (Mengel and Kirkby, 1982).
It seemed that high values of available macro and micronutrient concentrations in Gharbia soils when compared with Menofiya soils might be a result of higher organic matter in soil of the former than in the latter one. El-Fouly (1984) mentioned that the plants remove considerable amounts of macro and micronutrient yearly from the soil and not sufficient supplied with nutritional needs for giving maximum yield. This imbalanced fertilizer regime maximizes the negative effects of high pH and low organic matter (Serry, 1980).
Nutritional status in leaves: Data of total macro and micro nutrients content in leaves of Anna apple are presented in Table 3. It is observed that nitrogen content of leaves in most of samples taken from two locations was reflected the high N-dose applied. Leaves of the two locations showed a variation in their phosphorus content. Low values were shown for leaves of Gharbia G. as would be expected for high clay content, while the medium values were given for those of Menofiya G. These results are in harmony with those of Mengel and Kirkby (1982). On the other hand, Gahoonia et al. (1992), reported that application of phosphorus fertilizers to alkaline soil dose not always improve the phosphorus concentration in the leaves as the availability of this element in this soil is low.
Leaves from apple trees grown in both alluvial and newly reclaimed soils showed K-deficient concentrations (Table 3). This may be attributed to high application of N-fertilizer. Therefore, efficiency of plants in utilizing high concentration of K in soil is low. Numerous reports have shown that NH+4 nutrition reduce the uptake of K+ (Barker et al., 1967 and Kirkby, 1968). On the other hand Wadleigh and Richards (1951) concluded that decreasing soil moisture causes an increase in N-concentration in plant tissue and a decrease in K concentration.
The analysis of both soil and leaf samples for nitrogen, phosphorus and potassium and subsequent results of correlation between soil and plant contents of each element is intended to be used, later on, to suggest certain recommendations for fertilization with these elements.
Consequent to higher organic matter content in the first location, Fe-concentration was higher than in the second location, although the organic matter content was generally low.
The data further showed that leaves of apple were found deficient in Mn and Zn content at both locations (Table 3). This depression may be attributed to high Fe concentration and its interaction with each. This finding is in agreement with the findings of Wallace et al. (1986) and Baza et al. (1988). Biddulph (1953) suggested that the metal may be precipitated by P within the conducting tissue of the plant shoots and therefore would not be available to meet the plant’s nutritional requirements. Such low content may be attributed also to the increase in N supply, regardless of N sources, decreased the Zn content of tops (Ozanne, 1955). This may also be due to the retention of Zn in roots as a result of the formation of immobile Zn-protein complexes.
Concerning copper, it was found that the leaves of the former location contained more Cu concentration compared to the later. This result was related to Cu-concentration in the soils of both locations. The above-described results of micro nutrients status point to the necessity of giving more attention to micronutrient requirements of apple trees.
Table 4 presents the correlation coefficients between soil characteristics and leaf nutrient concentrations in Gharbia governorate. It is worth to mention here that highly significant and positive correlation coefficients were obtained between soil-K and leaf-P. In addition, a significant and negative correlation coefficients were found between Leaf-P and both O.M and soil-N, also between leaf-Mn and CaCO3 and Fe of soil content. The same was true between soil-Zn and leaf-K.
A highly significant positive correlation was observed between soil-K and leaf-Mn (Table 5). Soil pH of Menofiya governorate significantly correlated negatively and positively with Leaf-K and Fe, respectively, also significant positive correlation between soil-Cu and Leaf-K as well as soil-N and Leaf-P were found. On the other hand, a significant negative correlation was obtained between soil-Fe and leaf-Fe. Highly significant negative correlation was observed between pH and leaf-K reflecting the imbalanced nutrition and demand of trees to these elements.
Disorders in the balance between elements in the nutrient medium result in deficiencies and decrease in plant growth development. Thus, correction of plant nutrition disorders may be accomplished by foliar application with necessary nutrients (Miller et al., 1995).
In this respect, Ishag et al. (1989) and Mobarak and Abdalla, (1992) reported that correction of micro nutrients deficiency through foliar supply can improve the root growth.
The above mentioned results indicate the occurrence of imbalance nutrition not only in newly reclaimed soils (Sadat City) but also in alluvial soils (Tanta) leads to the conclusion that the disorder in the availability status of apple nutrients is a reflection of soil conditions especially pH, organic matter and clay contents such disorders limits the orchard productivity. In addition, iron may be a limiting factor of apple growth at both locations.
Acknowledgment
This study was conducted within the activities of the Egypto-German Project “Micro nutrients and Other Plant Nutrition Problems in Egypt”, which is carried out by the National Research Centre, Cairo (National Coordinator : Prof. Dr. M.M. El-Fouly) and Institute for Plant Nutrition, TU, Munich (Prof. Dr. A. Amberger) and sponsored by Egyptian Academy of Scientific Research and Technology and the German Ministry of Technical Cooperation through the German Agency for Technical Cooperation.