Browsing by Author "Hou, Fujiang"
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Item Allelopathy in an integrated rye-cotton-beef cattle system(2011-05) Li, Yue; Allen, Vivien G.; Chen, Junping; Hou, Fujiang; Hopper, Norman W.; Bednarz, Craig W.Small grain cover crops offer opportunities for grazing but effects of cover crops on the following row crop are not well understood. Beginning in 1998, rye (Secale cereale L.) planted alternately each September in a 2-paddock rotation, was grazed intermittently by steers from January until early April, was then chemically terminated, and cotton (Gossypium hirsutum L.) was no-till planted in May, in research conducted at New Deal, TX. Following cotton harvest, wheat (Triticum aestivum L.) was no-till planted, grazed out by Angus steers (Bos taurus) by June, and land was fallowed until rye was planted in September. By Feb 2006, wheat failed to establish and was omitted from the rotation. The experiment was a randomized complete block design with 3 replicates. Soil was primarily Pullman clay loam (fine, mixed, superactive, thermic Torrertic Paleustolls). Permanently located caged areas excluded grazing and were harvested as hay. In spring 2005, a second cage, adjacent to the original cage (2005) or randomly located in paddocks (2006 and 2007), investigated effects of 1) zero-grazed; 2) exclusion from grazing in 2005, 2007 or 2008 only; or 3) was always-grazed prior to cotton. In all 3 yrs, rye plant heights were taller (P < 0.01) in previously grazed than zero-grazed rye. Height of cotton plants in July were taller (P < 0.01) when planted into grazed than non-grazed rye in all years. Cotton lint yield in 2005 was greater (P < 0.01) when planted into grazed than ungrazed rye but differences were not significant in 2007 or 2008. Allelopathy was suspected. In a 3-yr small plot study, no-till planting cotton into rye or wheat cover crops reduced (P < 0.05) growth, lint and seed yield of cotton compared with no cover crop. Greenhouse trials verified cotton plant suppression by increasing rates of small grain residues and by direct application of 2-benzoxazolinone (BOA), a known allelopathic chemical. Allelopathic compounds, 2, 4-dihydroxy-7-methoxy-1, 4-benzoxazin-3-one (DIMBOA), 2-benzoxazolinone (BOA), 2, 4-dihydroxy-1,4-benxozaxin-3-one (DIBOA), from rye and wheat were detected in soil and plant material in greenhouse and field experiments. Grazing the cover crop by cattle may help alleviate these negative effects. Cover crops have environmental benefits but negative effects need further investigation.Item Dominant species as biological indicators to predict the changes of trace element in different types of rangeland(2022) Ning, Jiao; Liu, Shengsheng; Chang, Shenghua; Chen, Xianjiang; West, Charles P. (TTU); Hou, FujiangAlpine meadow, typical steppe and desert are globally important rangeland ecosystems. However, the seasonal variations in concentrations of trace elements, which are important nutrients for grazing livestock, are unclear in these types of rangeland and it is difficult to prevent disorders in grazing livestock caused by trace element excesses and deficiencies. In order to identify which forage species might serve as indicators of the trace element status of livestock forage, we investigated the seasonal trends in Fe, Mn, Cu, and Zn concentrations in the plant communities and dominant species from diverse rangeland types in northwest China in relation to livestock sufficiency levels. The trace element concentrations in the plant communities changed significantly with the season, with the highest Cu, Mn and Zn concentrations and the lowest Fe and Mn concentrations detected in spring and summer, respectively. The seasonal mean temperature, seasonal precipitation, and above-ground biomass significantly negatively correlated with the seasonal variation of Fe and Mn concentrations in the plant community. However, there was almost no significant correlation between these factors and the seasonal Cu and Zn concentrations. The plant concentrations of Fe and Mn were much higher than the recommended levels for livestock in all rangeland types, but the concentrations of Cu in the alpine meadow and the Zn concentrations in all the rangelands barely met the nutritional requirements for animal growth. Based on these deficiencies, we suggest that some forage species could be used as biological indicators to predict changes in the concentrations of trace elements. A decrease in the relative biomass of Kobresia capillifolia and Kobresia humilis in alpine meadows implies a decrease in the levels of Cu in the plant community. A decrease in the relative biomass of K. humilis in alpine meadows, an increase in Stipa bungeana in typical steppes and an increase in Nitraria tangutorum and Salsola passertine in desert rangelands lead to decreased concentrations of Zn in the plant community.