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[Objective] The study aimed to explore the relationship between weed diversity and soil factors in kiwifruit orchards under artificial disturbance, providing reference for formulating the accurate ecological weed control measures and ensuring the green production in orchards. [Method] The control and disturbed plots were set up. The a-species diversity indices and soil chemical indicators of these plot communities were measured, and the methods of redundancy analysis, canonical correspondence analysis and regression analysis were used to examine the effect of 'herbicide + manual weed control' disturbance on the coupling relationship between weed species diversity and soil factors. [Result] (i) The 25 weed species belonging to 15 families and 24 genera were recorded from five control plots, while 19 weed species belonging to 14 families and 18 genera were recorded from five disturbed plots, and the Asteraceae and Poaceae had the higher species richness. There was no significant difference in the four diversity indices between control and disturbed plots, however, the dominant weed changed from the native species Echinochloa crusgalli to the invasive species Alternanthera philoxeroides under disturbance. (ii) The redundancy analysis showed that the diversity indices had a negative relationship with soil pH, and disturbance further enhanced the determinant of pH on weed diversity. In disturbed plots, soil available phosphorus had a significant binomial fitting relationship with Simpson dominance index (R2 =0. 957, P=0.042) and Pielou evenness index (R2 =0.989, P=0.010), which all showed the convex trend. (iii) The canonical correspondence analysis showed that disturbance exacerbated the patchy aggregation distributions of weeds, and caused the determinants of weed distributions changing from soil pH and available potassium to available phosphorus and nitrate nitrogen, and led to an avoidance behavior of many weed species to the increasing nitrate nitrogen. In the canonical correspondence analysis diagram, the Digitaria sanguinalis and Solanum nigrum were all close to A. philoxeroides. [Conclusion] Maintaining a higher pH and available phosphorus content through soil improvement, planting native plants with strong resistance to prevent A. philoxeroides invasion through orchard grasses cultivation, and timely eradicating the nitrate nitrogen-preferred weeds are all beneficial for improving the quality and efficiency of weed control in kiwifruit orchards. [ABSTRACT FROM AUTHOR]

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BACKGROUND: Determination of ammonium nitrogen and nitrate nitrogen in soil makes great sense for indication of the nutrient status and environment evaluation of soil. The standard methods based on spectrophotometry are susceptible to interference from the color of the extraction test solution, turbidity, and other coexisting ions. Moreover, those methods are time - consuming due to the demand of decoloration. OBJECTIVES: To establish a convenient and high sensitivity method for the determination of ammonium nitrogen and nitrate nitrogen in soil, based on simultaneous extraction. METHODS: Ammonium nitrogen and nitrate nitrogen in soil were simultaneously extracted with KCl solution without decoloration, and determined by gas phase molecular absorption spectrometry. RESULTS: 50 samples were determined within Sh due to the avoidance of the color reaction process. The dynamic linear ranges of ammonium nitrogen and nitrate nitrogen were 0. 10 - 2. OOmg/L and 0. 20 - 4. OOmg/L, respectively. The detection limits were 0. 013mg/kg and 0. 002mg/kg, respectively. The recoveries ranged from 96. 3% to 100. 7%, and the relative standard deviation was below 1 % . CONCLUSIONS: Compared with the national standard method based on traditional spectrophotometry, this method has significantly improved the detection limit, precision and recovery. The method can be widely used in the field of detection of ammonium nitrogen and nitrate nitrogen in farmland soil. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Southwest China Journal of Agricultural Sciences is the property of Editorial Department of Southwest China Journal of Agricultural Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)