INTRODUCTION

Soil forms from rock in the first place, poor soil can be improved by adding specific types of rock dust chosen for their mineral content. The volcanic basalt, granite, dolomite rock phosphate and rock potash in the Alroc, slowly release a complete spectrum of minerals and trace elements which provides the perfect environment for natural farming. Since, rock in the long term improvement of their soil structure and increased productivity crops without negative affects on the environment.

Legumes respond well to rock phosphate grower's comment on the strong root systems, increased nodulation, good growth, report less fungal problems and increased crop production^[1-3]. However, Aboel-Soud et al.^[4], Mohamed^[5] and Shafeek et al.^[6] found that chemical phosphate application increased dry weight of shoots, number of pods, number of seeds/pod, pod length and weight also higher seed yield as well as NPK content of cowpea and broad bean plants as compared to those obtainer by rock phosphate. On the contrary, Kole and Hajra^[7] and Kotb et al.^[8] reported that no significant differences between the two sources of phosphate (Ca-super phosphate or rock phosphate) on plant growth and total yield.

Potassium application in poorly fertile soil is essential to obtained high yield, since it plays an important role in many processes in plant cells. It has a significant role in the activation of more than 60 enzymes which catalyze various metabolic processes^[9] up take and translocation nitrate from roots to shoots^[10]. Owing, to its role in many biochemical processes such as protein synthesis and carbohydrate metabolism. However, the highest growth, Yield, yield components, protein, N and K plant and seeds contents of legumes crop were obtained by adding 360 kg/fed natural rock potassium (feldspar) and no significant increase with recommended treatments^[11]. On the contrary, Siqueira et al.^[12] suggested that the potassium rock as such couldn’t be used as a potassium source for maize plant.

Therefore, the present research was conducted to determine the natural phosphate and potassium fertilizers to replace chemical fertilizer and to negative affects on the environment.

MATERIALS AND METHODS

Two different trials of experiments were conducted at the newly reclaimed soils in khatatba, Giza Governorate during winter growing season of 2003/2004 and 2004/ 2005 to study the effect of two sources of phosphate application (chemical super phosphate or natural rock phosphate) and two sources of potassium application (chemical potassium sulfate or natural rock potassium) on growth, yield components and seed chemical composition of pea plant.

The following treatments were conducted:

A split plot design with 4 replications was used. The experimental plot area as 10.5 m² and included 5 rows (each was 3.5 m length and 60 cm width). All treatments received the recommended dose of nitrogen (15 kg N/fed.) as ammonium sulfate 20.5% N twice, at planting and 30 days after planting. But, the chemical and the natural fertilizers were applied as one dose at planting 100 kg/fed of Ca super phosphate and 50 kg/fed of potassium sulfate and the natural rock fertilizers were used in 200 kg/fed of rock phosphate and 220 kg/fed of rock potassium. Recommended agronomic practices were followed. The seed of pea c.v. little marvel were inoculated with Risopum and were applied at a rate of 300 g per 60 kg seed, using Arabic gum solution (16%) as a sticking agent and were sown on the last week of October in both 2003 and 2004 seasons. The seeds were sown on one side of the ridge; 20 cm apart were performed according to Jackson^[13] (Table 1).

Five pea plants were uprooted from each plot after 60 days of sowing to assay plant length (cm), number of shoots and leaves per plant, fresh and dry weight of stems as (g/plant) as well as leaf area plant (cm²). Also foliage samples were taken to the determination of total pigments, i.e. chlorophyll a, d and carotene as (mg/100 g) fresh wt. according the methods decrypted by Wettstein^[14]. Pea pods were harvested weekly and at 3rd picking 10 pods sample were collected and the following assessment were written: number and average green pod weight (g/pod), number of seeds /pod and weight of 100 g seeds as well as the weight of green pods and the weight of seeds per plot were recorded.

Table 1:	Physical and chemical properties of experiment soil in 2003/2004 and 2004/2005 seasons

Sampler of green seeds were taken for the chemical determination of the elemental nutrition content, Whereas N, P and K were determined according to the procedure described by Koch and MC Meelin^[15], Trough and Meyer^[16] and Brown and Lilleland^[17], respectively. The total carbohydrate and crude protein were determined in green seeds using the method of AOAC^[18]. All obtained data values were subjected to the Analysis of Variance by Gomez and Gomez^[19].

RESULTS AND DISCUSSION

Plant growth characteristics: The presented data in Table 2 clearly showed that, mixture of phosphorus and potassium additions fertilizers had a superiority compared with the addition of either of alone. These results were true in the two experimental seasons and for all plant growth characters. The statistical analysis of the obtained data reveals that, the differences within the mixture of chemical and rock P and K treatments were enough to be significant at 5% level compared with either alone addition, concerning to all plant growth parameters in both seasons. In the same respect, the chemical form of phosphorus fertilizer (super phosphate) increased the plant length, number of stem and leaf area plant compared with rock phosphorus form fertilizer in both seasons.

Pea plant witch supplied with chemical form of P and K were more vigor than that plants supplied with rock form. This superiority might be attributed to the availability and speed solubility of chemical phosphorus and potassium form which hence the rooting system of pea plant directly absorbed it in short time^[20].

Table 2:	Effect of chemical and natural phosphate and potassium fertilisers on growth characters of pea plant

Table 3:	Effect of chemical and natural phosphate and potassium fertilisers on the pigment content in pea plant leaves

Table 4:	Effect of chemical and natural phosphate and potassium fertilisers on the yield and yield components of pea

Table 5:	Effect of chemical and natural phosphate and potassium fertilizers on the chemical composition of green seeds of pea

Also, the low effect of rock potassium fertilizer is due to its low K supplying capacity as shown by the total K uptake by the plant. These data support earlier studies using chemical extract ants in the laboratory and show the low availability of the K form this rock to maize plants^[12].

These results are in agreement with those obtained by other researcheers^[4-6,12] on the K effect.

Pigments content: The addition of mixture of phosphorus and potassium fertilizers for pea plant was statistically significant affected the pigment contents (Table 3). However, the content of total pigments (Chlorophyll a, b and carotene) increased to record their peaks with plants which received the P and K fertilisers compared to be added alone. These results held well in the two experiments of 2003 and 2004. The superiority in chlorophylls and carotene content with adding chemical P and K might be attributed to its important role in plant metabolism and the unknown minerals in rock P and K which could be inhibited plant growth and caused an inhibition in the absorption of other minerals and the low water solubility of rock phosphor and potassium maintain higher P and K concentration in soil solution due to its lower solubility^[5].

Table 3 clearly shows that plants of pea which supplied with P and K fertilizers in the chemical form had the higher values of chlorophylls and carotenes. These findings were true in both experimental seasons.

The greener pea plants which received chemical P and K may be attributed to the availability and the more solubility of chemical form of P and K compared to the rock one, consequently speed in its absorption by rooting system. It is known that, phosphorus and potassium has an important role in many bio chemical processes such as photosynthesis, respiration and protein synthesis and carbohydrate metabolism^[10].

Total pod yield and yield components: Table 4 indicates clearly that, adding P+K fertilizers resulted in an increase in number of pods plant, weight of pods per plot and weight of 100 seeds. These findings were true in the two experiments compared were added P and K alone. Moreover, the statistical analysis of the obtained data reveals that the different P+K treatments affected significantly total pods yield and its components in both seasons.

Chemical P and K added to pea plant resulted in the heavier weight of pods per plot in kg (10.62 and 10.97 for 1st and 2nd season, respectively) compared to the added rock form of P and K (10.20 and 10.86 kg/plot for the same respective seasons). Also, the chemical fertilizer recorded were 7.94 and 7.78 kg/plot of the green seeds of pea if compared by 7.06 and 6.93 kg/plot for the rock production in 1st and 2nd seasons, respectively.

The response of weight of 100 seeds followed the same pattern of change like that previous mentioned in both two experimental seasons. Moreover, the statistical analysis of the resulted data reveals that, the differences within the two forms of phosphorus and potassium were great enough to be significant at 5% level.

It could be concluded that, chemical P and K form has the heaviest and best pods yield. This might be attributed to the better plant growth and the higher pigments contents of the chemical P and K fertilizers compared to the natural (rock P and K) form and the limited solubility of rock phosphorus and potassium. In this connection, Romer and Lehne^[21] found that insufficient K supply to legumes may reduce their N₂ fixation capacity., consequently the total yield may also reduce. The response of total pods and seeds yield per plot of pea plant and its components to the P and K form followed the same pattern of change as that obtained by many researchers^[1-5] on the phosphorus effect and Ezzat et al.^[11]and Siqueira et al.^[12] in the potassium fertilizer effect.

Chemical composition of green seeds: The statistical analyses of the obtained data indicate that the differences within the two treatments of P+K fertilizers compared to added P or K added alone were enough to be significantly at 5% level. These were true in values of P and K in tissues of green seeds in both seasons. However, the response of N, Protein and vitamin C were not significant in the two seasons (Table 5) except the addition of mixture of the chemical form of P+K in both two seasons compared Concerning to the chemical composition of green seeds tissues of pea particularly P, K and vitamin C, the obtained data of both experiments shows that, their higher percentages were resulted with plants received P and K fertilizers in the chemical form. The other nutritional value, i.e. N and total protein in green seeds tissues recorded a fluctuation values within all treatments. In spite of the fluctuation and the in significant response of N and protein % to the fertilization of rock and/or chemical P and K fertilizers, the obtained data showed that, values of different nutritional values almost nearly. It could be concluded that, using rock fertilizer form of P and K gave nutritional values equal or little less than that, which were obtained when chemical form of P and K fertilizers were used.

The previous investigation on the benefits of rock and/or chemical P and K fertilizer particularly for the nutritional value of green seeds of pea tissues are in accordance with that reported by Ezzat et al.^[11] and Siqeira et al.^[12] on the potassium effect and Mohamed^[5] and Shafeek et al.^[6] on the phosphorus effect.

It could be concluded that using natural rock phosphorus and potassium fertilizers at reclaimed lands will give pod, seed yields and quality close to those obtained by chemical phosphorus and potassium application, with no significant difference between them. However, replacing the phosphorus and potassium by natural one will help in reducing environmental pollution and produce safe human food.