The Productivity and Soil Ecological Stoichiometry of Alfalfa with Water-harvesting Technique and Fencing Vegetation with Fertilizer Addition in the Semi-arid Loess Plateau
|Keywords||Alfalfa Litter Decomposition rate Fencing Semi- arid areas of the Loess Plateau|
In this paper, the semi-arid Loess Plateau (Yuzhong County, Gansu Province, Beishan area) ridge-furrow technology built artificial alfalfa grass and fencing of abandoned land successional vegetation for the object, by 2 years of Daejeon test ridge-furrow alfalfa grass hay production technology, water use efficiency, soil profile moisture dynamics, alfalfa roots and ground litter decomposition and nutrient characteristics of dynamic decomposition rate of response to rainwater harvesting techniques and soil ecological stoichiometry characteristics; preliminary study nutrient add fencing abandoned land succession vegetation aboveground biomass, belowground biomass, root to shoot ratio affect; nutrients add fencing vegetation soil ecological stoichiometry characteristics and vegetation construction. To this end, we conducted four experiments in Yuzhong County Beishan area. Experiment: ridge-furrow Alfalfa artificial grass soil moisture and grass amount, experimental five treatments: 1) CK: conventional flat ridge, no mulching (control); 2) M30: Lung and ditch width 30 cm, ridge covered with plastic film; 3) M60 ridge and groove width are 60 cm ridge covered with plastic film; 4) B30: ridge and groove width are 30 cm, and is not covered film; 5) B60: ridge and groove width to 60 cm, no mulching. Experiment II: alfalfa roots and shoots litter wild buried decomposition test experimental field decomposition experiment 5 processing. Experiment: rainwater harvesting measures buried decomposition of plant residue and roots, organic fertilizer wild experiment set two treatments: 1) F: plains ridging, no coating; 2) H: Ridge Building ridge and groove width of 60cm. Experiment 4: The role of nutrients to add the abandoned land fencing, vegetation, soil ecological stoichiometry characteristics of vegetation construction and experimental design of four treatments: 1) CK: no fertilizer (control); 2) N: add only nitrogen fertilizer; 3) P: only add phosphate fertilizer; 4) NP: add nitrogen and phosphate fertilizer at the same time. The main results are as follows: the experiment: 1) furrows with mulching (M60) can significantly improve the yield of alfalfa hay, alfalfa hay production but reduced bare treatment (B30, B60), the yield relationship between processing: M60 gt; M30 gt; CK gt; B60 gt; B30, the order of the size of this production with the previous seven years is consistent; M60 can improve the efficiency of water use;, M60 processing in high yield at the same time to ensure the shallow (0-100cm) soil moisture supplement. 2) planting alfalfa can effectively improve the 0-20cm layer of soil organic matter content; planting alfalfa will result in 0-20cm soil C / N ratio decreased, C / N ratio decreases will lead to soil organic matter decomposition was accelerated, resulting in reduced soil organic matter, In the present study, M60 treatment can be a good slow soil C / N decrease of 0-20cm. Experiment 2: 1) the the alfalfa root decomposition rate (K) is greater than the ground litter: KM60R (0.0029) gt; KM60L (0.0021), KM30R (0.0025) gt; KM30L (0.0012), KB60R (0.0025) gt; KB60L (0.0014) , KB30R (0.0023) gt; KB30L (0.0014), KCKR (0.0022) gt; KCJL (0.0014); alfalfa ground litter decomposition rate and initial litter N content, C / P was significantly positively correlated with initial The C / N was significantly negatively correlated. 2) alfalfa roots and shoots litter wild buried before 90d plant organic carbon decomposition rapid release, significantly lower than before decomposition of the organic carbon content, followed by the release of slowing decomposition 450d after M60 treatment litterfall organic carbon emission maximum ( 81.0g/kg). Alfalfa roots and shoots of all processing of buried litter decomposition 450d decomposition residues of N (B30 except), total P compared with the basal value (value before decomposition) increase performance for the enrichment of N, P prime accumulation. 3) wild litter bag buried alfalfa roots and ground litter decomposition 450d, C / N ratio were significantly lower for root residues, the C / N than to reduce the size of the magnitude as follows: M30 (9.70) gt; M60 (9.48) gt; CK (9.27) gt; B60 (8.41) gt; B30 (7.24); For ground litter, the C / N ratio of a reduction in turn is CK (9.59) gt; M30 (9.27) gt; B30 (7.91) gt; M60 (7.69) gt; B60 (5.69). 4) The decomposition rate of addition to the substrate chemical composition is closely related to, but also influenced by environmental factors, the experiment found that alfalfa roots and aerial litter decomposition rate and the 0-20cm layer of soil moisture was positively related (p lt; 0.05) . 5) litter bag field embedded after decomposition 450d, debris in the vicinity of 2-3cm 0-20cm soil layer soil organic matter (SOC) content increased SOC content of 0-20cm above the ground litter and root decomposition residues decomposition of SOC content of the residues; 0-20cm soil near the debris in the decomposition process of 2-3cm soil C / N ratio increases with the decomposition time increase the the M60 treatment the root decomposition 450d after residual soil C / N ratio (9.20), CK and M30 ground litter decomposition and soil C / N than minimum (8.50) In addition, the 0-20cm layer of the root debris near 2-3cm soil C / N ratio greater than The litterfall debris 0-20cm soil C / N ratio (B30 except for processing). 6) wild buried litter bag decomposition 450d the root debris near 2-3cm 0-20cm layer of soil available phosphorus trends: bare processing gt; CK gt; film processing, M60 treatment was the lowest, while litterfall The debris in 0-20cm soil available phosphorus content as follows: B30 (5.54mg/kg) ∽ the CK (5.33mg/kg) ∽ of the B60 (5.29mg/kg) gt; M30 (4.43mg/kg) gt; M60 ( 3.66mg/kg); decomposition 450d the root debris near 2-3cm 0-20cm soil layer C / P ratio is greater than ground litter residues 0-20cm soil C / P ratio, film processing residues The body near 2-3cm 0-20cm soil C / P ratio is greater than the bare treatment and control CK M60 processing C / P ratio, C / P ratio of CK minimum. Experiment III: five crops of wheat, corn, peas, alfalfa, potatoes and other plant residue and roots and the decomposition rate of organic fertilizer in the furrow coating rainwater harvesting processing greater than the ground not with mulching, the experiment also found embedded field The decomposition rate of 0-20cm soil moisture was positively correlated. Experiment 4: Add N fertilizer, P fertilizer could increase the fencing of abandoned land vegetation throughout the growing season, aboveground biomass aboveground biomass of P fertilizer treatment, and add four processing the highest, but add NP fertilizer treatment aboveground biomass and controls showed no significant difference; Add N fertilizer will aggravate soil water consumption, while the addition of P fertilizer, NP is conducive to the recovery of soil moisture. It was also found, add N fertilizer will make the 0-20cm soil SOC decreased 0-20cm soil C / N ratio decreased, while the addition of P fertilizer, the NP fertilizer can effectively improve the 0-20cm soil SOC and soil total nitrogen content, and can ease the 0-20cm soil C / N ratio reduction. Therefore, considering the production efficiency and ecological benefits, add P fertilizer is conducive to the restoration and construction of fencing uncultivated vegetation.