pH effects of the addition of three biochars to acidic Indonesian mineral soils

Abstract

Soil acidity may severely reduce crop production. Biochar (BC) may increase soil pH and cation exchange capacity (CEC) but reported effects differ substantially. In a systematic approach, using a standardized protocol on a uniquely large number set of 31 acidic soils, we quantified the effect of increasing amounts (0–30%; weight:weight) of three types of field-produced BCs (from cacao (Theobroma cacao. L.) shell, oil palm (Elaeis guineensis. Jacq.) shell and rice (Oryza sativa. L.) husk) on soil pH and CEC. Soils were sampled from croplands at Java, Sumatra and Kalimantan, Indonesia. All BCs caused a significant increase in mean soil pH with a stronger response and a greater maximum increase for the cacao shell BC addition, due to a greater acid neutralizing capacity (ANC) and larger amounts of extractable base cations. At 1% BC addition, corresponding to about 30 tons ha^?1, the estimated increase in soil pH from the initial mean pH of 4.7 was about 0.5 units for the cacao shell BC, whereas this was only 0.05 and 0.04 units for the oil palm shell and rice husk BC, respectively. Besides depending on BC type, the increase in soil pH upon the addition of each of the three BCs was mainly dependent on soil CEC (low CEC resulting in stronger pH increase), and to a lesser extent on initial soil pH (higher initial pH resulting in stronger pH increase). Addition of BC also increased the amount of exchangeable base cations (cacao shell ? oil palm and rice husk) and CEC. Through this systematic screening of the effect of BC on pH and CEC of acidic soils, we show that a small addition of BC, in particular if made of cacao shell, to acidic agricultural soils increases soil pH and CEC. However, the response is highly dependent on the type, quality and amount of the added BC as well as on intrinsic soil properties, mainly CEC.     

A drop in ambient temperature results in a transient reduction of interrenal ACTH responsiveness in the gilthead sea bream (Sparus aurata, L.)

This study investigated the effects of a drop in water temperature (18 °C to 9 °C in 24 h) on the pituitary and interrenal hormones of the gilthead sea bream Sparus aurata. The in vitro sensitivity of the interrenal tissue to ACTH, plasma levels of cortisol, ACTH, -MSH, GH, glucose, lactate and ions were determined. In vitro ACTH, stimulated the release of cortisol from isolated interrenal glands from control gilthead sea bream in a concentration dependent fashion. However, the interrenal cells were less sensitive to ACTH as soon as 24 h following the onset of the temperature drop. At this time, plasma cortisol and ACTH levels were raised, and plasma GH concentrations were decreased, whereas no significant changes were found in plasma -MSH. After 96 h plasma ACTH levels had recovered whereas plasma cortisol levels were still higher than controls after 8 days of the beginning of the experiment. Interrenal sensitivity had recovered after 8 days. The results may help to clarify the relationship between the stress response and the aetiology of the winter syndrome in sea bream.     

~（12）C~（6＋）重离子辐照对藏黄连幼芽生长情况的影响

通过0 Gy、15 Gy、30 Gy、45 Gy、60 Gy、75 Gy、90 Gy和105 Gy的12C6＋重离子束进行辐照,探讨其对藏黄连发芽、幼苗生长情况等方面的影响。结果表明,12C6＋重离子辐照能明显降低藏黄连种子的发芽势和发芽率,且剂量愈大,抑制作用愈明显,当辐照剂量低于30 Gy时,发芽势约为40%,高于75 Gy时,发芽率则低于25%;同时辐照处理组与对照组叶幅比差异不明显,呈现长形,均为箭状;辐照处理也对藏黄连植株高度产生了影响,未经辐射处理的藏黄连植株茎干的平均高度为10.87 cm,随着辐射剂量的加大,植株的茎干高度逐渐降低,辐照剂量达105 Gy时,植株高度为8.67 cm。     

新疆南部夏季高温的公路交通响应

通过对2008年夏季(6～8月)若羌模拟公路路面温度的实验数据及同期若羌气象观测资料的分析,得出:若羌模拟公路路面最高温度对交通运行有影响的概率高达73%,有很大影响和有严重影响的概率分别为40%,23%;在晴天12:00～18:00时,对交通运行有影响的概率达68%;日最高气温在37℃以上和35～37℃时,若羌模拟公路路面最高温度对交通运行有影响的概率分别达100%,87%.同时,利用塔克拉玛干沙漠周边公路沿线9个气象观测站(库尔勒、若羌、且末、民丰、和田、叶城、喀什、阿克苏、库车)近48年(1961-2008年)5～9月气温和地面温度资料,对其气候概况和气候变化特征进行分析,得出近48年夏季最高地面温度总体为上升趋势,尤其是20世纪80年代以后上升幅度较大.     

Impacts of rising atmospheric carbon dioxide on model terrestrial ecosystems

In model terrestrial ecosystems maintained for three plant generations at elevated concentrations of atmospheric carbon dioxide, increases in photosynthetically fixed carbon were allocated below ground, raising concentrations of dissolved organic carbon in soil. These effects were then transmitted up the decomposer food chain. Soil microbial biomass was unaffected, but the composition of soil fungal species changed, with increases in rates of cellulose decomposition. There were also changes in the abundance and species composition of Collembola, fungal-feeding arthropods. These results have implications for long-term feedback processes in soil ecosystems that are subject to rising global atmospheric carbon dioxide concentrations.