Evaluation of the Efficiency of Animal Manures in the Production of Thyme (Thymus daenensis L.)

Sustainability of production in agricultural lands is directly related to soil fertility management. In this regard, the application of livestock manure is a very important method in improving soil fertility without adversely affecting the environment. Although the efficiency of these manures could be sustained for several growing seasons, however their efficiency at the first year is principally more important due to the direct relationship with the production of that year. Therefore, the present study was conducted to evaluate the effect of source and amount of manure on the growth and production of thyme.

The experiment was performed as a split plot design in time and in the form of a randomized complete block with three replications at the model cultivation site of medicinal plants of Koohrang Agriculture-Jahad in 2018 and 2019. Experimental treatments were included three levels of poultry manure (100, 143 and 250 kg N/ ha; PM100, PM143, PM250), three levels of sheep manure (100, 143 and 250 kg N/ ha; SM100, SM143, SM250)), three levels of cattle manure (100, 143 and 250 kg N/ ha; CM100, CM143, CM250) and chemical fertilizer (CF) and no fertilizer application (C) as positive and negative controls, respectively, which in two cutting were compared. The measured traits were includedphotosynthetic pigments, leaf area index, aerial biomass, essential oil content and essential oil yield. Data was analyzed by SAS software and means were compared by LSD test.

In both cuttings, the amount of chlorophyll a in plots received medium and high level of animal manures were similar to plot received chemical fertilizer. Except to CM250 treatment, chlorophyll b in all manure treatments were similar to CF treatment. In the first cutting, the leaf area index in PM250, SM143 and SM250 treatments had a significant advantage compared to CF treatment, but in the second cutting, manure treatments (except SM100) did not show a significant difference comparing to CF treatment. Thyme biomass obtained from PM250, SM143 and SM250  treatments had a significant advantage compared to CF treatment in the first cutting, but in the second cutting, there was no significant difference among manures and CF treatments. In the first cut, the essential oil content of medium and high levels of poultry manure and also high levels of sheep and cattle manures were significantly higher than the CF treatment. However, in the second cutting, the amount of essential oil under all levels of poultry manure and medium and high levels of sheep and cattle manures were higher than the CF treatment. In the first cutting, the essential oil yield of medium and high levels of poultry and sheep manures and high level of cattle manure were higher than that the CF treatment, but in the second cutting, only high level of poultry manure had a significant advantage in comparison with CF treatment. The fertilizer application efficiency regarding to biomass production was similar for all fertilizer treatments, except SM143. The highest fertilizer use efficiency in the production of essential oil was obtained with SM143 and PM143, respectively.

Applying a medium amount of sheep manure could be more effective in the crop ecosystem due to its superior efficiency in comparison with other levels of this fertilizer and other studied animal manure and chemical fertilizers. However, if the essential oil yield of the thyme be the gold of the farmer, the high level of poultry manure has priority over the balanced level of sheep manure, although the efficiency of this level of poultry manure is 35% lower than the balanced level of sheep manure. Therefore, in addition to producing the essential oils, the efficiency of fertilizers could be also considered as an important factor, regarding to achieving the sustainable aspects in the medicinal plants ecosystems.