RESUMEN
Taking soils in a long-term experimental field over 29 years with different land uses types, including arable land, bare land, grassland and larch forest land as test materials, the distribution and storage of soil organic carbon (SOC) in the profile (0-200 cm) in typical black soil (Mollisol) region of China were investigated. The results showed that the most significant differences in SOC content occurred in the 0-10 cm surface soil layer among all soils with the order of grassland > arable land > larch forest land > bare land. SOC contents at 10-120 cm depth were lower in arable land as compared with the other land use types. Compared with arable land, grassland could improve SOC content obviously. SOC content down to a depth of 60 cm in grassland was significantly higher than that in arable land. The content of SOC at 0-10 cm in bare land was significantly lower than that in arable land. Although there were no significant differences in SOC content at 0-20 cm depth between larch forestland and arable land, the SOC contents at 20-140 cm depth were generally higher in larch forestland than that in arable land. In general, SOC content showed a significantly negative relationship with soil pH, bulk density, silt and clay content and an even stronger significantly positive relationship with soil total N content and sand content. The SOC storage in arable land at 0-200 cm depth was significantly lower than that in the other three land use types, which was 13.6%, 11.4% and 10.9% lower than in grassland, bare land and larch forest land, respectively. Therefore, the arable land of black soil has a great potential for sequestering C in soil and improving environmental quality.
Asunto(s)
Secuestro de Carbono , Carbono/análisis , Bosques , Pradera , Suelo/química , ChinaRESUMEN
A greenhouse sand culture experiment was conducted to study the effects of citric acid, oxalic acid, malic acid, and their mixture on the nitrogen accumulation, nodulation, and nitrogen fixation of soybean. After the application of test low molecular weight organic acids, the nitrogen accumulation in the aboveground part of soybean decreased by 17.6%-44.9% at seedling stage, 29.8%-88.4% at flowering stage, 9.18%-69.6% at podding stage, and 2.21%-41.7% at maturing stage). In the meanwhile, the nodule number, nitrogenase activity, and leghemoglobin content decreased by 11.4%-59.6%, 80.5%-91.7%, and 11.9%-59.9%, respectively, resulting in a significant decrease (9.71%-64.5%) of nitrogen fixation of soybean, compared with the control. The inhibitory effect of test low molecular weight organic acids increased with their increasing concentration. Oxalic acid had a higher inhibitory effect than citric acid and malic acid, and the mixture of the three organic acids had an enhanced inhibitory effect.
Asunto(s)
Ácido Cítrico/farmacología , Glycine max/metabolismo , Fijación del Nitrógeno/efectos de los fármacos , Nitrógeno/metabolismo , Fósforo/deficiencia , Malatos/farmacología , Ácido Oxálico/farmacología , Estrés FisiológicoRESUMEN
A static absorption method was used to study the influence of soluble carbon and nitrogen on ammonia volatilization from different thermal zone soils, such as black soil, red soil and cinnamon soil, performed in laboratory. Results showed that nitrogen application enhanced ammonia volatilization significantly. The amount of ammonia volatilization in cinnamon soil ranged from 14.3 to 7.37 mg x kg(-1), which in black soil from 1.52 to 1.11 mg x kg(-1) and from 0.998 to 0.402 mg x kg(-1) in red soil applied with only nitrogen or nitrogen amended with soluble carbon. Moreover, soluble carbon decreased ammonia volatilization caused by nitrogen, and amounts of decrease were 27.0%, 48.5%, 60.0% in black soil, cinnamon soil and red soil separately. The amount of ammonia volatilization from black soil and cinnamon soil applied only nitrogen was in an order of CK > NPK > NPKOM, while contrary order appeared if nitrogen was amended with soluble carbon. However, it was the same order for red soil applied with only nitrogen or nitrogen amended with soluble carbon. In addition, the variances of NH4+ -N and NO3- -N contents in cinnamon soil were larger than other soils, which suggested that cinnamon soil had high potential of nitrogen loss.
Asunto(s)
Amoníaco/química , Carbono/análisis , Fertilizantes , Nitrógeno/análisis , Suelo/análisis , Agricultura/métodos , Calor , Solubilidad , VolatilizaciónRESUMEN
In this paper, black soil samples at the depths of 0-20 cm and 20-40 cm were collected from the Hailun Agricultural Ecology Station of Chinese Academy of Sciences to study the effects of long-term fertilization on their urease, invertase, phosphatase and catalase activities and total C and N contents. The results showed that long-term application of chemical fertilizers and organic manure increased the activities of urease, invertase and phosphatase in 0-20 cm and 20-40 cm soil layers in different degree, and the combined application of them increased the activities of the three enzymes significantly, with an increment of 43.6%-113.2%, 25.9%-79.5% and 14.7%-134.4% in 0-20 cm soil layer and 56.1%-127.2%, 14.5%-113.8% and 16.2%-207.2% in 20-40 cm soil layer, respectively. However, long-term application of chemical fertilizers without organic manure had little effects on catalase activity. The activities of urease, invertase and phosphatase decreased with increasing soil depth. Long-term application of N fertilizer increased urease activity, and P fertilization had obvious positive effect on phosphatase activity. Long-term fertilization also had obvious effects on the soil total C and N contents and C/N ratio.
Asunto(s)
Fertilizantes , Suelo/análisis , Ureasa/metabolismo , beta-Fructofuranosidasa/metabolismo , China , Productos Agrícolas/enzimología , Productos Agrícolas/crecimiento & desarrollo , Monoéster Fosfórico Hidrolasas/metabolismo , Factores de TiempoRESUMEN
Based on the long-term field experiment at Hailun Agro-ecosystem Experimental Station of Chinese Academy of Sciences, this paper studied the cadmium (Cd) accumulation, its development tendency, and Cd availability in black soil under effects of long-term application of chemical N and P fertilizers and pig manure. The results showed that under no fertilization, soil Cd concentration had a slight increase. Long-term chemical N and P fertilization increased soil Cd concentration significantly, but soil Cd accumulation had less difference under different N and P fertilization rates. Applying pig manure increased the Cd accumulation in soil significantly, and the accumulation had a tendency of speed-up. Cd-containing feedstuff additives could be the important source of Cd in pig manure. No significant effects of chemical N and P fertilization were observed on the Cd availability in soil, but long-term application of pig manure increased the Cd availability significantly.