For the last twenty years, the world's rapeseed production has had a stable growth. This crop is an important source of renewable energy, and new conditions are created for the use of oilseed rape (Ralphe et al., 2006; Günnur and Nilgün, 2013). The main manufacturers are China, India, Canada, and the EU (Carrе and Pouzet, 2014). This culture has been adapted to the western conditions of the USA. Edaphoclimatic conditions of Russia allow growing the rapeseed plants in all the regions (Karpachev, 2009). The seeds fund development demands the constant improvement of this culture cultivation technology in the concrete edaphoclimatic conditions taking into account the breed peculiarities, the reaction on the different technological elements including the reaction on both mineral and organic fertilizers (Pin Koh and Ghazoul, 2008; Rondanini et al., 2012). The researches results prove that the greatest impact on rapeseeds productivity is caused by the norm of a nitrogen fertilizer application, and the smallest – by the previous culture and the fertilizer type, as well as the interaction between these processing factors (Rathke et al., 2005). Organic animal waste is recognized as a valuable source of plant nutritional chemicals in farming systems and plays a certain role in the improvement of the soil using organic substances (Schoenau and Davis, 2006). Therefore, the further development of rapeseed cultivation technologies with organic and mineral fertilizers usage is currently important. Also, there is growing interest in the use of rapeseed for food development. The focus is on the composition of the protein and lipids contained in rapeseed. (Gunhild et al., 2000; Arif et al., 2012). Moreover, there is very little research on the effect of zeolite and poultry manure when growing rapeseed on seed mineral composition.

Therefore, our research aimed to study the composition of ash elements in rapeseed under agroecological experiments.

We analyzed the content of 9 elements in the rapeseed ash - K, P, Mg, Ca, Mo, Mn, Zn, Fe, and S (shown in Table 1). The predominant elements were P and K.

The decreasing series of elements in the rapeseed ash is as follows: P ≈ K > Mg ≥ Ca > Mo > S > Zn > Mn > Fe. Our results are comparable to the data obtained by the authors (Calısır et al., 2005). Studies (Gins et al., 2018) showed that the main elements in the seeds of amaranth are also K, Ca, but the order of their accumulation is different.

The proportion of P is from 10.852 mass % (control) till 11.855 mass % (zeolite 5 t.ha^-1). High content of P in the rapeseed ash was also noted in the experimental variants using hen droppings 5 t.ha^-1; N₆₀:P₆₀:K₆₀ + zeozeolite 5 t.ha^-1 and hen droppings 5 t.ha^-1 + zeolite 5 t.ha^-1. (Figure 2). The content of P in seeds is an important and only source available to maintain the initial growth of seedlings of future plants (Manske et al., 2001; Masoni et al., 2007; Fageria, Baligar and Jones, 2010). The accumulation of P in the seeds is determined by bioavailability, the ability of the roots to absorb P from the soil, and plant growth rates (Lynch 2007; Hammond and White 2008; White, 2013).

According to White and Veneklaas (2012), increasing P content in seeds can improve plant formation and increase yield rape. K in the seed ash contains from 9.933 mass % (zeolite 5 t.ha^-1) till 12.34 mass % (N₆₀:P₆₀:K₆₀) (Figure 2).

It was determined that the accumulation of K in the control was 25% lower than in the variant with the mineral fertilizer (N₆₀:P₆₀:K₆₀) and 20% lower than in the variant with the combined mineral fertilizer (N₆₀:P₆₀:K₆₀ + zeolite 5 t.ha^-1) application. K is a macroelement that is responsible for the regulation of the majority of metabolic reactions that low in living organisms. K controls osmotic pressure transmembrane potential, charges equilibrium, cathodeanion balance, pH – everything that the homeostasis of cells and tissues consists of.

In the ionic form, K can be found in all the organs, tissues, and cell structures in concentrations that exceed the concentration of other ions (Meathnis et al., 1997).

In Figure 3 the comparative data of Mg, Ca, and Mo concentrations are presented. Mg activates a large number of enzymes that take part in the processes of CO₂ and N assimilation. Mg is necessary for the keeping up of the cathode-anion balance and pH regulation. In the cell wall and the seeds membrane, Mg²⁺ is coordinately connected with carboxylic groups of pectin substances and takes part in the creation of the inner physiological environment of plants. Mg, Ca and N are localized in the seed membrane. ATP, phosphoinositol (phytin) in combination with Mg are accumulated in the seeds in the form which is comfortable for storage (Nechaev, Trauberg and Kochetkova, 2007). The concentration of Mg in the rape speed fluctuates from 4.733 mass % (control) to 5.575 (zeolite 5 t.ha^-1). In the variants of the experiment with the mineral and organic N application the concentration of Mg in the rapeseeds increases by 20 – 25% in comparison with the control.

Ca is indispensable within the plant for the stabilization of cell walls and maintenance of membrane integrity. A high proportion of calcium is located in the cell walls. It is involved in the regulation of the cation/anion-balance (IPI Bulletin). The concentration of Ca in the rapeseed fluctuates from 4.012 mass % (control) to 4.843 mass % (N60:P60:K60+ zeolite 5 t.ha^-1).

Mo fulfills many useful functions for the organism: it is a cofactor and an activator of oxidases (xanthine oxidase and serine oxidase), which takes part in the synthesis of the amino acid (Avtsyn et al., 1991). The concentration of Mo in the rapeseed fluctuates from 4.178 mass % (control) to 5.558 mass % (N₆₀:P₆₀:K₆₀ +zeolite 5 t.ha^-1).

Sulfur plays an indispensable role in rape plant metabolism as a component of proteins and glucosinolates. S is essential for protein formation, important for high protein content in rapeseeds. Not only the amount of protein but also the quality of protein is influenced by the S-status of plants. Because of the central role of sulfur and nitrogen in the production of proteins, there is a close relationship between the supplies of S and N in plants (Blake-Kalff et al., 2000). The concentration of S in the rapeseeds is rather high and varies from 0.993 to 1.275 mass %. Depending on the experimental variant the content of S in the seeds fluctuates insignificantly (Table 1). The proportion of Zn does not exceed 0.305% mass and also fluctuates insignificantly depending on the variant of the experiment. Mn is a co-factor and activator of many enzymes and possesses antioxidant activity. In the rapeseeds the concentration of Mn is 0.058 mass % (control) – 0.303 mass % 9 (hen droppings 5 t.ha^-1). In the experimental variants with the application of the fertilizer, the concentration of Mn is 2 – 6 times higher than the control (Table 1). Organic Fe is an essential compound for the human organism this element s a part of catalytic centres of many oxidationreduction enzymes (Shmalko and Roslyakov, 2011).

In the rapeseeds, the concentration of Fe varies from 0.034 mass % (the control) to 0.159 – 0.215 (the variant with the complex composition of fertilizers), Table 1. Thus, we have found that the content of manganese and iron in rape seeds increases significantly when grown in the variants of the experiment with the introduction of zeolite and hen droppings. Fordoński et al. (2016) research also showed that the micronutrient content (Mn, Zn, Cu, and Fe) of winter oilseed rape increased significantly in response to an increase in nitrogen fertilization doses.

The low variation coefficient 10 – 25% is determined for P, Mg, and S; K and Ca are characterized with the middle variation coefficient 35 – 36%. The low and average variation coefficient is typical for biologically significant elements of seed rape and indicates the accumulation stability of the elements. Zn, Mn, and Fe are marked with the high variation coefficient

Calculated correlation coefficients between elements (Table 2). It is established that there is a high correlation between elements, for example, K and Mo (r = 0.96); P and Mg (0.86) and P and Fe (r = 0.94); C and Mo (r = 0.86). The mean correlation is between Ca and Mn, Mo, and Fe (r = 0.78); between K and Zn, Mg and Fe (r = 0.76); between P and Mo (r = 0.69); Mn and Fe (r = 0.67); P and Ca (r = 0.61); Mo and Mn (r = 0.60); S and Zn (r = 0.56 – 0.57). Weak correlation found between between S and Zn (r = 0.52); between K and Ca (r = 0.32); K and Mg (r = 0.19): Ca and S (r = 0.17) and S and Mn (r = 0.16).

It is noted that the accumulation of P, Ca, Mo, and S in seeds leads to a decrease in Zn. These results are consistent with data from Szczepaniak et al. (2017).

Research conducted in agro-ecological experience the influence of zeolite and chicken droppings on the formation of the mineral composition of rapeseed has been established. Using the method of the energy dispersive Xray spectrometry the new data about the variety of the rapeseeds mineral composition were received, the proportion of the elements in the ash was determined, the variation coefficients were calculated. In variants of the experiment with hen droppings, 5 t.ha^-1, and N₆₀:P₆₀:K₆₀ +hen droppings, 5 t.ha^-1 the content of P, Ca, Mo, S, Mn, and Fe are 2 – 4 times higher than in the control. The influence of the experimental variants on the accumulation of potassium in rape seeds has not been established. A high correlation has been established between the elements K and Mo, P and Mg, P and Fe, C and Mo. It was noted that the accumulation of P, Ca, Mo, and S in rape seeds leads to a decrease in the Zn content.