Application of Improved Interferometry on Low SNR Data to Auto-pick First Arrivals

Three improvements are added to the traditional super-virtual refraction interferometry. Inverse correlation functions are used to enhance the quality of near-offset traces. Interferometry in common-receiver gathers increases the stacking fold. Wavelet shaping effectively suppresses spurious events. The improved interferometry increases the SNR of first arrivals on both synthetic data and real exploration data. We then add two methods to distinguish the spurious events and real events on super-virtual data by event consecutiveness and inexistence of spurious events in raw data. With improved interferometry and improved auto-picking process, we can accurately auto-pick first arrivals over an expanded aperture of low SNR data.EI

Fertilization increases paddy soil organic carbon density*

Field experiments provide an opportunity to study the effects of fertilization on soil organic carbon (SOC) sequestration. We sampled soils from a long-term (25 years) paddy experiment in subtropical China. The experiment included eight treatments: (1) check, (2) PK, (3) NP, (4) NK, (5) NPK, (6) 7F:3M (N, P, K inorganic fertilizers+30% organic N), (7) 5F:5M (N, P, K inorganic fertilizers+50% organic N), (8) 3F:7M (N, P, K inorganic fertilizers+70% organic N). Fertilization increased SOC content in the plow layers compared to the non-fertilized check treatment. The SOC density in the top 100 cm of soil ranged from 73.12 to 91.36 Mg/ha. The SOC densities of all fertilizer treatments were greater than that of the check. Those treatments that combined inorganic fertilizers and organic amendments had greater SOC densities than those receiving only inorganic fertilizers. The SOC density was closely correlated to the sum of the soil carbon converted from organic amendments and rice residues. Carbon sequestration in paddy soils could be achieved by balanced and combined fertilization. Fertilization combining both inorganic fertilizers and organic amendments is an effective sustainable practice to sequestrate SOC