Műtrágyázás hatása a lucerna (Medicago sativa L.) elemfelvételére karbonátos homoktalajon | The effect of fertilisation on the element uptake of alfalfa (Medicago sativa L.) on carbonated sandy soil
2010
Kádár, Imre
Summary We examined the effect of fertiliser treatments on the development, weeds and hay yield of alfalfa, as well the ammonium-lactate – acetic acid soluble PK content of the soil between 2000 and 2001, in years 31–34 of the NPK fertilisation experiment established on carbonated sandy soil in the Danube-Tisza mid-region in 1970. The ploughed layer of the production site contains about 1% CaCO ₃ and humus and 5–10% clay. The subsoil is strongly calcareous. Soil water can be found 5–7 m deep, the area is drought-sensitive and weakly supplied with soluble nutrients (N, P, K). The main conclusions of the experiment are as follows. The ammonium-lactate – acetic acid (AL) soluble PK content of the soil (that has not been fertilised for 29 years) is low: as a result of the soil-enriching PK fertilisation, the AL-PK content is 150–200 mg kg-1 AL-P ₂O ₅ in the surface soil and the AL-K ₂O content is in or above the “satisfactory” range. The average element content of alfalfa hay between each mowing showed the following minimum – maximum values: 3–6% N; 2–4% Ca; 0.32–0.56% Mg; 0.26–0.43% S; 0.25–0.41% P. Microelements: Fe 160–360; Al 101–301; Sr 123–194; Mn 83–223; Na 28–107; B 25–67; Zn 16–39; Ba 6–20; Cu 4–10; Ni 0.4–2.0; Pb 0.3–0.7; Mo 0.3–0.5; Co 0.1–0.3 mg kg-1. The Se content was generally 0.4 mg kg-1, whereas As, Hg, Cd were below the 0.1 mg kg-1 limit of detection. The leaf diagnostics supply limit values in the reference section could be used in determining the level of nutrient supply of alfalfa and indirectly in assessing the nutrient supply of the soil, therefore, its fertiliser need can also be estimated. In our experiment, the average contents of N (above 3.5%), K (above 2.5%) and P (above 0.3%) showed a satisfactory degree of supply in the green phase of hay, that was in accordance with the literature. During the four years and as a result of eight mowings, the yield of the non-fertilised control plot was 6.8 t ha-1, whereas that of the plot that received abundant fertilisation was 12.5 t ha-1. Accordingly, the total element uptake was 197–479 kg N, 102–372 kg K, 177–286 kg Ca, 33–53 kg Mg, 20–39 kg P, 16–43 kg S, 2–4 kg Fe and Al, 1–2 kg Mn and Sr per hectare. The harvested yield during the four years removed 729 g Na, 402 g B, 251 g Zn, 136 g Ba, 57 g Cu, 13 g Ni, 5–5 g Pb and Cr, 4–4 g Mo and Se, and 2 g Co per hectare on average. The quantities of As, Hg, and Cd were below the 1 g ha-1 limit of detection. The specific element content needed to produce 1 t hay averaged over eight mowings and the four years was 29–37 kg N, 20–26 kg Ca (28–36 kg CaO), 15–30 kg K (18–36 kg K ₂O), 3–5 kg Mg (5–8 kg MgO), 2.5–3.0 kg P (6–7 kg P ₂O ₅) and 2.5–3.5 kg S. Our data could serve as a guideline for the calculation of the element demand of the planned yield in consultancy, also taking into account the atmospheric N-binding of alfalfa. The raw protein content of alfalfa hay increased from 17% to 24–27% with NPK fertilisation. Its raw fibre, raw ash, raw sugar and raw fat content did not significantly change as a result of the treatments, whereas its carotin content doubled. The carotin content of alfalfa hay was higher than the grass hay without papilionaceae by a magnitude. Furthermore, it contained 2–3 times more protein, 2 times more raw fat, 40% more ash and 20% more raw sugar on average, whereas its raw fibre content was half as much as that of grass hay. The nutritional value of alfalfa is high, it can partially substitute concentrated forage.
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