Tailings are the residue of mined material after separation of metals such as copper, gold and silver elements. Separation of minerals involves crushing of the host material to fine particles and separation of the met...Tailings are the residue of mined material after separation of metals such as copper, gold and silver elements. Separation of minerals involves crushing of the host material to fine particles and separation of the metals by flotation or other technique. The total amount of tailings produced by Freeport Indonesia from their Grasberg mine is about 230,000 tons/day. These tailings are deposited in a lowland area and are confined by two levees. There are two types of plant growth on inactive tailings according to land use （natural succession area or reclaimed agricultural area）. This study of soil fertility on the mine tailing was required to contribute to information on the management oftailings. Representative sampling locations were chosen based on particle size distribution with soil （0- 5 50 cm depth） being subjected to laboratory analysis. Total N soil is very low （〈 0.02%）, CEC （≤20 me/100 g） low to medium, and organic-C ranges from 0.1-2%. oH is 7-8 resulting in the low availability of some nutrients, but values of extractable Cu may be high （≥ 300 mg/kg）. Nutrient elements are more abundant in soils on fine textured tailings.展开更多
Arbuscular mycorrhizal(AM) symbionts are able to greatly affect soil fertility. However, the relationships between AM symbiosis development levels and citrus mycorrhizosphere soil fertility remain weakly known in fiel...Arbuscular mycorrhizal(AM) symbionts are able to greatly affect soil fertility. However, the relationships between AM symbiosis development levels and citrus mycorrhizosphere soil fertility remain weakly known in field. In our study, AM colonization, spore density, hyphal length density, and glomalin-related soil protein(GRSP) content in citrus(Robertson naval orange grafted on Citrus reticulata Blanco) orchards along an altitudinal gradient were investigated seasonally in southern China. The results showed that AM colonization and abundances of spore and hyphae fluctuated significantly in different seasons and altitudes. The highest AM colonization(83.03%) was observed in orchards at 200 m above sea level in summer, spore density(16.8 spores g-1soil) in orchards at 400 m in autumn, and hyphal length density(2.36 m g-1soil) in orchards at 600 m orchards in summer; while the lowest values(43.60%, 2.7 spores g-1soil and 0.52 m g-1soil of AM colonization, spore density, and hyphal length density, respectively) were all observed in orchards at 800 m in winter. Correlation analyses demonstrated that the soil properties such as soil organic matter,alkali-hydrolyzable N, available P, and p H were significantly(P < 0.05) positively correlated with either citrus total AM colonization or the abundances of spore and hyphae. GRSP was significantly(P < 0.05) positively correlated with soil organic matter and p H.Redundancy analysis supported that soil environmental factors such as altitude, GRSP, soil organic matter, and alkali-hydrolyzable N severely(Monte Carlo permutation tests, P = 0.002) influenced AM colonization and abundances of spore and hyphae in citrus orchards. Our data demonstrated that soil environmental factors are vital in determining AM symbiosis development in citrus orchards.展开更多
文摘Tailings are the residue of mined material after separation of metals such as copper, gold and silver elements. Separation of minerals involves crushing of the host material to fine particles and separation of the metals by flotation or other technique. The total amount of tailings produced by Freeport Indonesia from their Grasberg mine is about 230,000 tons/day. These tailings are deposited in a lowland area and are confined by two levees. There are two types of plant growth on inactive tailings according to land use （natural succession area or reclaimed agricultural area）. This study of soil fertility on the mine tailing was required to contribute to information on the management oftailings. Representative sampling locations were chosen based on particle size distribution with soil （0- 5 50 cm depth） being subjected to laboratory analysis. Total N soil is very low （〈 0.02%）, CEC （≤20 me/100 g） low to medium, and organic-C ranges from 0.1-2%. oH is 7-8 resulting in the low availability of some nutrients, but values of extractable Cu may be high （≥ 300 mg/kg）. Nutrient elements are more abundant in soils on fine textured tailings.
基金supported by the China Spark Program of the Ministry of Science and Technology,China(No.2007EA760023)
文摘Arbuscular mycorrhizal(AM) symbionts are able to greatly affect soil fertility. However, the relationships between AM symbiosis development levels and citrus mycorrhizosphere soil fertility remain weakly known in field. In our study, AM colonization, spore density, hyphal length density, and glomalin-related soil protein(GRSP) content in citrus(Robertson naval orange grafted on Citrus reticulata Blanco) orchards along an altitudinal gradient were investigated seasonally in southern China. The results showed that AM colonization and abundances of spore and hyphae fluctuated significantly in different seasons and altitudes. The highest AM colonization(83.03%) was observed in orchards at 200 m above sea level in summer, spore density(16.8 spores g-1soil) in orchards at 400 m in autumn, and hyphal length density(2.36 m g-1soil) in orchards at 600 m orchards in summer; while the lowest values(43.60%, 2.7 spores g-1soil and 0.52 m g-1soil of AM colonization, spore density, and hyphal length density, respectively) were all observed in orchards at 800 m in winter. Correlation analyses demonstrated that the soil properties such as soil organic matter,alkali-hydrolyzable N, available P, and p H were significantly(P < 0.05) positively correlated with either citrus total AM colonization or the abundances of spore and hyphae. GRSP was significantly(P < 0.05) positively correlated with soil organic matter and p H.Redundancy analysis supported that soil environmental factors such as altitude, GRSP, soil organic matter, and alkali-hydrolyzable N severely(Monte Carlo permutation tests, P = 0.002) influenced AM colonization and abundances of spore and hyphae in citrus orchards. Our data demonstrated that soil environmental factors are vital in determining AM symbiosis development in citrus orchards.
