Effects of amendments on base cation and micronutrient availabilities in soils planted with tomato in a solar greenhouse

In order to obtain high tomato production, chemical fertilizers have been intensively applied in solar greenhouse in Northern China. This unreasonable use of chemical fertilizers always leads to soil degradation. One of the most serious problems is the loss of exchangeable base cations: calcium (Ca), magnesium (Mg), and potassium (K), and available micronutrients: iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn). We collected soils with different tomato cultivation durations: 0, 5, and 20 years, to investigate the effects of different fertilizers on the dynamics of soil base cations and micronutrients which extracted by 1 M ammonium acetate and 0.005 M diethylenetriaminepentaacetic acid, respectively. Five treatments were included: no fertilizer application as control (Con), chemical nitrogen, phosphorus and potassium fertilizers (CF), rice straw (FS), chicken manure (CM), and vermicompost (VM). Our results show that soil exchangeable Ca significantly decreased with the increase of cultivation duration, whereas soil exchangeable K increased due to the fertilization of K. Soil exchangeable Ca and K exhibited decreasing trends during the growth season of tomato, but not exchangeable Mg. Long-term tomato cultivation significantly increased soil available micronutrients. Soil available Fe and Mn fluctuated sharply during the growing season of tomato plant. Except Zn, fertilizers exhibited no constant significant effect on base cations and micronutrients. After long term planting of tomato, the loss of exchangeable Ca, but not Mg and micronutrients, might potentially constrain the productivity of crop under intensive chemical fertilization.