The Drought Vulnerability Of Cropping Systems In Black Soil Region Of Northeast China

Black Soil Region of Northeast China as an important agricultural zone forcommercial and economic crop in China suffered from increased drought riskwhich seriously threatened agricultural production and food security in recentdecades. Therefore, how to evaluate the drought hazard on grain yield is an urgentproblem to be solved. Vulnerability framework as powerful stress analysis tool,has been widely used in the field of agricultural hazard analysis. Accordingly, inthe present paper, we used the vulnerability framework to assess the droughtvulnerability over Black Soil Region of Northeast China by combined with thetemporal and spatial analysis of drought variation and regional productivitysimulation.Based on the reliable statistical methods of the Mann-Kendall test, Sen’sslope and the Standardized Precipitation Index (SPI), we analyzed the temporaland spatial variation of drought occurrence during the crop-growing season (fromMay to September) and summer (from June to August). The results showed thatregional mean precipitation during the crop-growing season and summer over thelast forty years has decreased at the rate of-1.72mm/year and-1.12mm/year,respectively. According to timescale analysis of abrupt changes, there were twodistinct time series (1965-1983and1996-2009) with decreasing precipitationtrends at a95%confidence level. A comparison between the two time series ofthese two periods demonstrated that more frequent and more severe droughtoccurred during1996-2009. Furthermore, drought risk in recent decades hasbecome even more serious both in severity and extent. Especially in thecrop-growing season of2001and summer of2007, over25%(2.0×105km2) ofstudy area experienced severe drought (serious and extreme droughts).Regional productivity were simulated by Crop-C model. Based on theexperiments at Dehui and Hailun stations, the key parameter of this stations wereestablished and adjusted. Through the modeling calibration and validation againstthe long-term data of yield, the key parameter (α) for Maize and Soybean overBlack Soil Region of Northeast China were found to be17and8, respectively.With regard to the process of key parameter establishment and adjustment, the modeling value for Maize over the both experiment stations show higher precisethat for Soybean. With regard to the process of the calibration and validation oflong-term data of yield, the results accordingly explain the modeling precision.Overall, relatively precise of modeling value for both of two crops indicated thismodel can be applied to Black Soil Region of Northeast China for simulating theecosystem productivity.Combined with the spatial analysis of serious drought during2007,long-term drought exposure and the yield simulation of two crops, we spatiallyassessed the drought regional vulnerability over Black Soil Region of NortheastChina during2007by used SUST vulnerability model. The drought during2007as one of severe droughts in recent years, different levels of drought occurredover80%(3.5×104km2) of this region. Thereinto, most part of these region weresuffered from serious drought; The drought exposure was calculated by statisticsof long-term analysis of drought occurrence. Drought occurred over90%of studyarea at1.0-2.0times per decade; The production modeling results of two croppingpattern over this indicated that there was a increasing trend between northern andsouthwestern part of study region for Maize and Soybean. The yield reductionmainly occurred in northern and middle region (most parts of Heilongjiangprovince); the results of SUST vulnerability implied both of two crop patternexisted high drought vulnerability over most parts of Heilongjiang province andSiping city (Jilin province). the results highlight the urgent need for thedevelopment of effective drought adaptations (drought-tolerant crop varieties andirrigation system) for high drought vulnerability region over northeast China.Based on laboratory experiments, we discuss the Drought adaptive strategyfor Soybean. The obtained results are as follows: with regard to the experiment ofphosphorus fertilizer, the optimum application is30mg/kg, while high applicationunder drought condition may cause stress on Soybean growth. For the experimentof precipitation pattern, increased40%precipitation is benefit for biomassaccumulation of soybean. On the contrast, decreased precipitation observablyreduce the biomass of roots and aboveground. The results of phosphorus fertilizerand precipitation pattern combined treatment demonstrate that long interval of precipitation improved Soybean biomass. Meanwhile, the results of two factorsanalysis of variance implied the effects of precipitation pattern were more benefitthan phosphorus fertilizer for accumulating biomass and developing root.