Usable agricultural land is receding worldwide due to soil carbon and nutrient loss and adverse environmental conditions. Potentially mitigating effects of soil amendments toward this were examined for Terra preta, Perlhumus, and biochar. The focus was on nutrient transfer and productivity of German barley cultivar (Lexy) at different growth parameters, especially water deficiency, as one of the most harmful abiotic ecological stresses that affects crop yield and productivity. Barley seeds were germinated and placed in pots in greenhouse conditions. Nutrient-poor sandy substrate was enriched with carbon by the application of the soil amendments at two levels (0.1%, 1%C-concentration). After 4-week growth period, half of the pots were subjected to drought stress to observe the response to water deficiency. Scaling up, barley was germinated in marginal sandy substrate mixed with the abovementioned soil-additives (0.1% C) inside larger bins (>1m depth) outdoors. All treatments were opti mized to 90kgN/ha using Hakaphos blue. The results showed a significant increase in the shoot fresh weight, with carbon content increasing in pots. The highest values were in (1% C) Terra preta (42.2g). The soil amendments application reduced the negative effect of drought on the root dry weight, which led to the highest value (1% C) in Terra preta (Normal: 7.1g, drought: 0.655g) compared to control. Perlhumus and Terra preta addition showed increased soil nitrogen content compared to their control. In the outdoor experiment, nutrient-enriched biochar treatment showed the highest seed yield (14193 seeds/m2) compared to control. Seed ripening was latest in Perlhumus, which had similar effect as the control (no C-addition). Generally, increasing the carbon concentration improved seed germination and plant growth positively regarding different soil additives. Also, future research into soil amendments to enhance barley cultivar productivity in challenging environmental conditions in la rge-scale field experiments is still needed to explore and understand such effects further.
Najjar et al. (Wed,) studied this question.