| The development of grassland and ecological animal husbandry in the karst rocky desertification areas is one of the effective measures to improve the ecological environment and development economic in the short term,and it is an important part of the project for rock desertification project.However,due to the easy degradation of artificial grassland after planting and the backwardness of cattle and sheep feeding methods,grassland and ecological animal husbandry is failed to give fully play to its role in rocky desertification control.Therefore,it was studied the improvement mechanism of degraded grassland,the coupling mechanism of degraded grassland improvement and semi-house feeding cattle and sheep to restore grassland productivity,improve grassland ecological environment as well as efficient and reasonable breeding mode,and realize the coordinated and healthy development of grassland and animal husbandry.Based on the systematic coupling theory of geography,karst science,grassland science,animal husbandry,ecology and other interdisciplinary disciplines,two typical representative demonstration areas of rocky desertification environment in south China were selected as the study area-Salaxi demonstration area with potential-middle rocky desertification of karst plateau-mountain in Bijie and Guanling-Zhenfeng demonstration area with moderate-intensive rocky desertification of karst plateau-canyon in Huajiang,the literature analysis method,research visit method and comprehensive analysis method were used to determine the orchardgrass(dactylis glomerata)grassland in the Salaxi demonstration area of Bijie,the emperor bamboo(pennisetum sinese)grassland and the alfalfa(Medicago sativa)gralassland in the Guanling-zhenfeng demonstration area of Huajiang,3 typical degraded grasslands were subjected to improvement experiment of defoliation and fertilization.The improvement experiment of defoliation and fertilizationwas carried out three times on the degraded grassland,potassium sulfate(including K44%)and urea(including N46%)were applied after each defoliation,the fertilization ratio of potassium fertilizer and nitrogen fertilizer was set to 60 kg/hm2: 60 kg/hm2,40 kg/hm2: 80 kg/hm2,30 kg/hm2: 90 kg/hm2 and the control group(no fertilization).The semi-house feeding and grazing experiment was carried out on the perennial ryegrass(Lolium perenne)grassland in the Salaxi demonstration area in Bijie,the grazing time of the semi-house feeding and grazing experiment was set to grazing for 4h,6h,8h and the control group(no grazing,full day supplement),the cattle and sheep were supplemented and supplemented with total mixed ration(TMR)after grazing.The experimental data were analyzed by comparative analysis,one-way ANOVA and multi-factor analysis of variance to clarify the improvement mechanism of degraded grassland,the coupling mechanism of degraded grassland improvement and semi-house feeding cattle and sheep,and to form and demonstrate the key techinologies of degraded grassland improvement and semi-house feeding cattle and sheep.The following conclusions were drawn:1.The soil physical and chemical properties of the orchardgrass grassland in the Salaxi demonstration area of Bijie and the emperor bamboo grassland and the alfalfa gralassland in the Guanling-zhenfeng demonstration area of Huajiang were significantly different before and after the fertilization improvement(except for the control group).After the improvement experiment of mowing and fertilization,soil water content,field water holding capacity,capillary water holding capacity,total porosity and capillary porosity of three degraded grassland increased significantly(P<0.05)when the the the ratio of potassium fertilizer and nitrogen fertilizer was 60 kg/hm2: 60 kg/hm2,there was no significant difference in the soil bulk density in the control group.Compared with before improvement,the p H of soil in the orchardgrass grassland in the Salaxi demonstration area of Bijie was significantly increased,but it wassignificantly decreased in the emperor bamboo grassland and the alfalfa gralassland in the Guanling-zhenfeng demonstration area of Huajiang(P<0.05).The contents of total nitrogen,total potassium,hydrolyzable nitrogen and available potassium in each fertilization treatments in the two demonstration areas were generally higher than those in the control group,and the total phosphorus and available phosphorus in different fertilization treatments were generally low.Soil organic matter was the highest and significantly higher than the control group when the ratio of potassium fertilizer and nitrogen fertilizer fertilization was 60 kg/hm2: 60 kg/hm2(P <0.05).2.After the improvement experiment of mowing and fertilization of the orchardgrass grassland in the Salaxi demonstration area of Bijie and the emperor bamboo grassland and the alfalfa gralassland in the Guanling-Zhenfeng demonstration area of Huajiang,the fresh grass yield and hay yield of different fertilization treatment in three degraded grassland increased with the mowing times,that was 3rd stumbble>2nd stumbble>1st stumbble,and there was significant difference among the treatments of each stubble(P<0.05).The fresh grass yield of orchardgrass,emperor bamboo and alfalfa was higest when the the ratio of potassium fertilizer and nitrogen fertilizer was 60 kg/hm2: 60 kg/hm2,and it was significantly higher than other treatments(P<0.05).But the forage quality was decreased with the mowing times,that was 1st stumbble>2nd stumbble>3rd stumble,the crude protein content of each stubble was higest and the crude fiber content was lowest when the the ratio of potassium fertilizer: nitrogen fertilizer was 60 kg/hm2: 60 kg/hm2,and there was significant difference among the treatments of each stubble(P<0.05).3.The soil physical and chemical properties of the perennial ryegrass grassland after semi-house feeding and grazing in the Salaxi demonstration area of Bijie changed more and more with the increase of grazing time.Compared with pre-grazing,the physical properties of grassland in controlgroup and grazing grassland for 4 hours were not significantly different(P>0.05);the soil physical properties of grassland(except soil bulk density)increased significantly and it was significantly higher than the control group after 6 hours of grazing cattle and sheep(P<0.05);after grazing cattle and sheep prolonged to 8h per day,the soil water content,field water holding capacity,capillary water holding capacity,total porosity and capillary porosity of grassland was decreased significantly and it was significantly lower than the control group(P<0.05),the soil bulk density increased significantly and significantly higher than the control group(P<0.05).The total nitrogen,total potassium,hydrolyzable nitrogen and available potassium of soil in the grassland grazing for 4h,6h and 8h were significantly lower than those in the control group(P<0.05),that was control group>grazing 4h>grazing 6h>grazing 8h,but the total phosphorus and available phosphorus of soil in the grassland grazing for 4h,6h and 8h increased significantly and it was significantly higher than the control group(P<0.05),that was grazing 8h>grazing 6h>grazing 4h>control group.The soil organic matter increased at first and then decreased with the extension of grazing time and it was reached its maximum after grazing 6h,after grazing time exceeded 6h,the organic matter was decreased significantly,that was grazing 6h>grazing 4h>control group>grazing 8h.4.The fresh grass yield and hay yield were the highest in the perennial ryegrass after 6h of grazing cattle and sheep,it was lowest after 8h of grazing cattle and sheep.The fresh grass yield and hay yield in the perennial ryegrass after grazing cattle was characterized by grazing 6h>control group> grazing 4h>grazing 8h,it was characterized by grazing 6h>grazing 4h>control group>grazing 8h after grazing sheep,at the same time,there were more weeds in the control group and grassland grazing for 4 hours,and there was was basically free of weeds in the grassland grazing for 6h and 8h.During the experiment,the overall trend of weight gain of cattle and sheep increased with the grazing time,the weight gain range of cattle was between 72 kg and 103.5kg,and the weight gain range of sheep was between 13.05 kg and 16.59 kg,the weight gain of cattle and sheep in the control group was lowest.The weight gain of cattle and sheep supplemented after grazing 6h was reached the maximum,the weight gain of cattle and sheep supplemented after grazing 8h was slightly lower than that grazing 6h,but it was still higher than that control group and grazing 4h,which was characterized by grazing 6h + TMR > grazing 8h + TMR > grazing 4h + TMR >control group.5.The key techniques suitable for the degraded grassland improvement and semi-house feeding of cattle and sheep in rocky desertification area were put forward,and the results obtained were demonstrated.According to the existing and common techniques of degraded grassland improvement and semi-house feeding of cattle and sheep in two demonstration areas,it was put forward key innovative techniques of fertilization improvement technology,semi-house feeding improvement technology,the design of roof structure for cattle and sheep pen,feeding through for cattle and sheep,the device of drinking water for cattle and sheep,the device for sport ground of sheep raising,the device of grazing eviction and driving-back for sport ground of sheep raising,in this paper.Since the experiment was carried out,the area of degraded grassland improvement with coordinated development of ecological restoration and economic in the Salaxi demonstration area of Bijie was completed about 24.55 hm2,the area of degraded grassland improvement with balancing ecological restoration and economic development was completed about 14.5 hm2,and the demonstration effect was obvious. |
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