Verifiable soil organic carbon modelling to facilitate regional reporting of cropland carbon change: A test case in the Czech Republic

Regional monitoring, reporting and verification of soil organic carbon change occurring in managed cropland are indispensable to support carbon-related policies. Rapidly evolving gridded agronomic models can facilitate these efforts throughout Europe. However, their performance in modelling soil carbon dynamics at regional scale is yet unexplored. Importantly, as such models are often driven by large-scale inputs, they need to be benchmarked against field experiments. We elucidate the level of detail that needs to be incorporated in gridded models to robustly estimate regional soil carbon dynamics in managed cropland, testing the approach for regions in the Czech Republic. We first calibrated the biogeochemical Environmental Policy Integrated Climate (EPIC) model against long-term experiments. Subsequently, we examined the EPIC model within a top-down gridded modelling framework constructed for European agricultural soils from Europe-wide datasets and regional land-use statistics. We explored the top-down, as opposed to a bottom-up, modelling approach for reporting agronomically relevant and verifiable soil carbon dynamics. In comparison with a no-input baseline, the regional EPIC model suggested soil carbon changes (~0.1–0.5 Mg C ha−1 y−1) consistent with empirical-based studies for all studied agricultural practices. However, inaccurate soil information, crop management inputs, or inappropriate model calibration may undermine regional modelling of cropland management effect on carbon since each of the three components carry uncertainty (~0.5–1.5 Mg C ha−1 y−1) that is substantially larger than the actual effect of agricultural practices relative to the no-input baseline. Besides, inaccurate soil data obtained from the background datasets biased the simulated carbon trends compared to observations, thus hampering the model's verifiability at the locations of field experiments. Encouragingly, the top-down agricultural management derived from regional land-use statistics proved suitable for the estimation of soil carbon dynamics consistently with actual field practices. Despite sensitivity to biophysical parameters, we found a robust scalability of the soil organic carbon routine for various climatic regions and soil types represented in the Czech experiments. The model performed better than the tier 1 methodology of the Intergovernmental Panel on Climate Change, which indicates a great potential for improved carbon change modelling over larger political regions

Crystallization and preliminary crystallographic characterization of the extrinsic PsbP protein of photosystem II from Spinacia oleracea

Degradation-free crystalization of thrombin-digested recombinant His-tagged PsbP protein of photosystem II from Spinacia oleracea resulting in crystals diffracting to 2.06 Å

The effect of nitrogen and sulphur fertilization on yield and quality of kohlrabi (Brassica oleracea, L.) Efeito da adubagem com o nitrogénio e enxofre ao rédito e à qualidade das couves-rábanos (Brassica oleracea, L.)

In a greenhouse pot experiment with kohlrabi, variety Luna, we explored the joint effect of N (0.6 g N per pot = 6 kg of soil) and S in the soil (25-35-45 mg kg-1 of S) on yields, on N, S and NO3- content in tubers and leaves, and on alterations in the amino acids concentration in the tubers. S fertilisation had no effect on tuber yields. The ranges of N content in tubers and leaves were narrow (between 1.42-1.48 % N and 1.21-1.35 % N, respectively) and the effect of S fertilisation was insignificant. S concentration in the tubers ranged between 0.59 and 0.64 % S. S fertilisation had a more pronounced effect on the S concentration in leaf tissues where it increased from 0.50 to 0.58 or to 0.76 % S under the applied dose. The NO3- content was higher in tubers than in leaves. Increasing the S level in the soil significantly reduced NO3- concentrations in the tubers by 42.2-53.6 % and in the leaves by 8.8-21.7 %. Increasing the S content in the soil reduced the concentration of cysteine + methionine by 16-28 %. The values of valine, tyrosine, aspartic acid and serine were constant. In the S0, S1, and S2 treatments the levels of threonine, isoleucine, leucine, arginine, the sum of essential amino acids and alanine decreased from 37 to 9 %. The histidine concentration increased with increasing S fertilisation. S fertilisation of kohlrabi can be recommended to stabilize the yield and reduce the undesirable NO3- contained in the parts used for consumption.<br>Deficiência aguda de S no solo tem sido observada na Europa desde os anos 1980. O couve-rábano é uma das plantas com maior exigência nesse nutriente e sua interação com o N é frequentemente relatada na literatura. Este trabalho foi conduzido em casa de vegetação visando testar o efeito da aplicação de S, na presença de N, na produção e qualidade de couve-rábano (Brassica oleracea, L., variedade Lua). As plantas foram cultivadas em vasos contendo 6 kg de solo, aos quais foram aplicados 0,6 kg de N e S para se obter os teores no solo de: 25 (teor natural), 35, ou 45 mg kg-1. Foram avaliadas a produção e o teor de N, S e NO3- nas raízes e nas folhas e as alterações no teor de aminoácidos nas raízes. A produção de raízes do couve-rábano não afetada pela adubação com S. O teor de N nas raízes e nas folhas variou de 1,42-1,48 % e de 1,21-1,35 % de N, respectivamente, não sofrendo efeito significativo da adubação com S. O teor de S nas raízes oscilou entre 0,59-0,64 % de S. A aplicação de S influenciou positivamente o seu teor no tecido foliar, que apresentou estreita relação com os teores do nutriente no solo, chegando a 0,50; 0,58 e a 0,76 % de S, respectivamente, para os três teores testados. O teor de NO3- foi maior nas raízes do que nas folhas. O aumento das doses de S reduziu o teor de NO3- nas raízes, em 42,2 a 53,6 %, e nas folhas em 8,8 a 21,7 %. O aumento do teor de S no solo reduziu o teor de cisteína + metionina em valores que variaram de 16 a 28 %, mas não afetou os teores de valina, tirosina, ácido aspártico e serina. Com a variação dos teores de S entre 25 e 45 mg kg-1 , houve decréscimo de treonina, isoleucina, leucina, arginina, e a soma de amino ácidos esenciais e alanina na faixa de 37 a 9 %. O teor de histidina aumentou com a elevação do teor de S no solo. A adubação do couve-rábano com S é recomendada sobre tudo para a estabilização da produção e para a redução dos teores de NO3-, cuja presença em alimentos é indesejada