Search

Laboratory experiments were conducted to determine the influence of three types of decomposing fresh organic materials [pig manure (PM), Astagalus sinicus (AS), and Alternanthera philoxeroides (AP)] on dissolution of Fe2O3 and ZnO and also the use of a loamy calcareous soil as an alternative source of iron (Fe) and zinc (Zn). Levels of Fe and Zn concentrations in composting solutions changed with composting time. The maximum levels of solution Fe resulting from the decomposition of the three organic materials were 20, 612, and 348 mg L−1 for PM, AS, and AP, respectively, when the soil was supplied as the Fe source, and 17, 32, and 16 mg L−1 when Fe2O3 was supplied as the Fe source. Corresponding maximum levels of solution Zn were 0.9, 0.7, and 1.3 mg L−1 and 35, 171, and 103 mg L−1 when the soil and ZnO was supplied as the Zn source respectively for the same three organic materials.

In order to understand the behavior of water soluble organic matter (WSOM) in soil under different types of forest, soil samples from twenty sites were sampled and analyzed for each forest in the area of Huzhou, China. Each sample was extracted with both cool water (25°C) and hot water (100°C). Without exception, hot water soluble organic carbon (HWSOC) was more than cool water soluble organic carbon (CWSOC). Chinese fir forest soil contained 1.49 times more CWSOC and 1.34 times more HWSOC than did the masson pine forest soil. The CWSOC and HWSOC in soil under Chinese fir forest account for 1.11% and 1.60% of total soil organic carbon (TSOC), and 0.70% and 1.19% under masson pine forest soil, respectively. CWSOC under Chinese fir forest was closely related to SOM and microbial biomass carbon (MBC) (correlation coefficients were 0.474* and 0.482* respectively), HWSOC, however, has little to do with SOM, MBC and soil enzymatic activities. HWSOC under masson pine forest was generally associated with SOM, MBC...

Phyllostachy praecox is a major bamboo species which produces a small-type of bamboo shoot, one of the most delicious forest vegetables in China. Emergence of bamboo shoots of Phyllostachy praecox usually begins in late January to early February but most shooting does not occur until March. Mulching in winter is commonly adopted to achieve earlier emergence of the bamboo shoots. However, with mulching the plantation of bamboo trees appears to develop early senescence. This could be a result from “disordered” changes of soil chemical and/or biochemical properties. A field experiment was conducted to understand the mechanism. Three commonly used mulching materials, rice straw (RS), mixture of rice straw and rice grain hulls (RH) and leaves of bamboo trees (BL) were applied in December. A control plot without covering (CK), was also established. Dynamic changes of soil chemical properties and soil enzymatic activities were monitored through winter to spring by collecting soil samples at 25 day intervals. The...

Low root temperature has previously been reported to induce boron (B) deficiency in some species but the mechanism is not entirely clear. Using B‐specific resin to buffer B concentrations in solution, we found that decreasing root zone temperature (RZT) from 27 to 12°C for 6 days depressed sunflower (Helianthus annuus L.) dry matter, root length, root to shoot ratio and B uptake. Boron uptake into the shoots was depressed at 12°C RZT to a greater relative extent than dry matter. Furthermore, B partitioning to young leaves decreased with low RZT, particularly at 12°C RZT. The external B requirement for shoot growth increased with low RZT. Leaf functioning was impaired by low B supply as measured by K+ leakage from the youngest mature leaf blade, whereas it was much less affected by RZT, and there was no effect of RZT on B ‐ adequate plants. By contrast, root function was impaired more by low RZT than low B. Therefore, we predict that higher rates of B application will be required for plant growth when soil temperature is below a critical threshold, which for sunflower was about 17°C. Conversely, practices which increase soil temperature above the threshold may also improve plant B nutrition.