Severe Spring Drought Research Articles

Assessing the Spatial–Temporal Pattern of Spring Maize Drought in Northeast China Using an Optimised Remote Sensing Index

Northeast China plays a pivotal role in producing commodity grains. The precipitation and temperature distribution during the growth season is impacted by geographical and climate factors, rendering the region vulnerable to drought. However, relying on a single index does not reflect the severity and extent of drought in different regions. This research utilised the random forest (RF) model for screening remote sensing indices. Relative soil moisture (RSM) was employed to compare seven commonly used indices: the temperature vegetation dryness index (TVDI), vegetation supply water index (VSWI), vegetation condition index (VCI), temperature condition index (TCI), vegetation health index (VHI), multi-band drought index (MBDI), and normalised difference drought index (NDDI). The effectiveness of these indices for monitoring drought during different developmental stages of spring maize was evaluated. Trend rates were employed to investigate the temporal changes in drought patterns of spring maize from 2003 to 2020, and the Sen + Mann–Kendall test was used to analyse spatial variations. The results showed the following: (1) The seven remote sensing indices could accurately track drought during critical growth stages with the TVDI demonstrating higher applicability than the other six indices. (2) The application periods of two TVDIs with different parameters differed for the drought monitoring of spring maize in different developmental periods. The consistency and accuracy of the normalised difference vegetation index (NDVI)-based TVDI (TVDIN) were 5.77% and 34.62% higher than those of the enhanced vegetation index (EVI)-based TVDI (TVDIE), respectively, in the early stage. In contrast, the TVDIE exhibited 13.46% higher consistency than the TVDIN in the middle stage, and the accuracy was the same. During the later stage, the TVDIE showed significantly higher consistency and accuracy than the TVDIN with consistency increases of 9.61% and 38.64%, respectively. (3) The drought trend in northeast China increased from 2003 to 2020, exhibiting severe spring drought and a weakening of the drought in summer. The southern, southwestern, and northwestern parts of northeast China showed an upward drought trend; the drought-affected areas accounted for 37.91% of the study area. This paper identified the most suitable remote sensing indices for monitoring drought in different developmental stages of spring maize. The results provide a comprehensive understanding of the spatial–temporal patterns of drought during the past 18 years. These findings can be used to develop a dynamic agricultural drought monitoring model to ensure food security.

Influence of the North Kazakhstan Plains Weather on the Productivity of the Spring Soft Wheat

Spring soft wheat is a primary agricultural crop of North Kazakhstan, the growing process of which is done in harsh weather conditions due to the fact, that early spring drought and the biggest rainfalls at the end of June and beginning of July, are normal in the region. Due to this fact, scientists and producers have mistakenly believed that in the Northern region, spring wheat should be sown later, adjusting the main phase of plant development “tillering – stem elongation” under the maximum summer rainfalls. The research aims to establish the dependence of spring wheat yield on the amount of spring-summer rainfall at different sowing periods. The following methods were used in the research: field method, methods of clustering, variation, correlation and dispersion analysis. Analysis of observations from 2012-2021 showed that years with an early-spring drought and mid-summer maximum rainfalls were less than one-third of ten and about 60% were years with no spring drought, although the maximum rainfall period was shifted to the June month. However, only one year (10%) was characterized by a severe spring drought and a shift of summer rainfalls to August. The highest yield (26.9 c/ha) of the studied wheat species was observed in years with an atmospheric precipitation shift at the beginning of the summer period and early sowing date. During years of early spring drought with the biggest rainfall in mid-summer, relatively high yields (20.5 cwt/ha) are observed in the later sowing dates. The practical value of the research is determined by the fact, that in Northern Kazakhstan the sowing dates of spring wheat are not closely tied to the calendar dates and depend significantly on the climatic conditions of the region and the weather conditions that prevailed in the spring and summer period of a specific year

Influence of cover crop on water and nitrogen balances and cash crop yield in a temperate climate: A modelling approach using the STICS soil-crop model

Cover crops are crucial to diversify cropping systems into more agroecological systems by providing ecosystem services, such as reduction of nitrate leaching, provision of a green manure effect, and soil carbon storage. However, they can influence water drainage and nitrogen (N) or water availability for the succeeding crop, depending on their management and the climate. In this simulation study, we used the STICS model to predict the influence of cover crop species, date of sowing and termination, and cover crop residue management on N and water balances, and the yield and stress of the succeeding cash crop. We performed 25-year simulations for five contrasting sites in south-western France, which is a temperate region of Europe with dry summers. As expected, cover crops decreased nitrate leaching effectively but also decreased drainage by a mean of 5–40 mm. This decrease depended mainly on the sowing and termination dates, while the decrease in nitrate leaching varied greatly among sites and depended most on sowing date, followed by cover crop species and then termination date. Cover crops had little influence on soil water content in the upper 0.1 m of soil at sowing of the succeeding cash crop, but decreased soil water content of the total soil profile by 0–30 mm. Soil water content depended most on termination date, followed by species and then site. Total soil mineral N content (SNC) also decreased, by 5–40 kg N.ha−1, at the three driest sites and up to 10 kg N.ha−1 at the rainiest site. Termination date, the second-most influential factor on SNC, indicated that later termination resulted in lower SNC than that after bare soil. N uptake by the succeeding cash crop depended on species and termination date, and a legume cover crop and earlier termination date resulted in higher N uptake. The decrease in maize and sunflower yield was due mainly to changes in the N stress index during the vegetative phase for maize, and both vegetative and reproductive phases for sunflower. No water stress or increase in irrigation volumes was predicted or was correlated with yield changes, except at dry sites for the few years that experienced a severe drought in spring. While cover crops decreased nitrate leaching effectively, they decreased drainage and could induce N stress for the succeeding crop, particularly in dry regions. Including legumes in mixtures and adapting the termination date to local climate conditions could decrease or avoid these negative effects.

Different Effects of Spring and Summer Droughts on Ecosystem Carbon and Water Exchanges in a Semiarid Shrubland Ecosystem in Northwest China

Extensive revegetation and conservation programs have been initiated in semiarid desert areas in northern China for over 10 years. However, our knowledge on how drought affects the desert ecosystem carbon (C) and water exchanges is limited. Based on eddy covariance measurements, we evaluated the effect of spring and summer droughts on ecosystem C and water exchanges over a semiarid Artemisia ordosica shrubland in Northwest China for 2014–2016. Over the 3 years, the ecosystem was a weak source of C (40 ± 32 g C m−2 y−1) (mean ± standard deviation) with evapotranspiration (ET) of 310 ± 65 mm y−1. Annual net ecosystem production was − 76, − 25 and − 18 g C m−2 y−1 and water use efficiency (WUE) [gross ecosystem production (GEP)/ET] was 0.92, 1.14 and 1.09 g C kg−1 H2O in 2014, 2015 and 2016, respectively, indicating greater C loss and suppressed WUE in 2014. We found that GEP, Re and ET were significantly suppressed in year 2014 when a severe spring drought occurred, as compared to the year 2016 with summer droughts. The differences in C and water fluxes between years 2014 and 2016 were greater than those between years 2015 and 2016, although the ecosystem suffered a severe summer drought in 2015. Interannual differences in GEP were likely due to differences in leaf area index and canopy conductance, both of which were decreased by drought. Our results indicated that spring drought appears to be more critical to the C balance than summer drought in this semiarid shrubland. This suggested that under future climate change with more variable precipitation and frequent droughts expected in northern China, the timing of drought may be critical to the C and water balances.

Response of ecosystem carbon fluxes to drought events in a poplar plantation in Northern China

Poplar plantations are widely used for timber production and ecological restoration in northern China, a region that experiences frequent droughts and water scarcity. An open-path eddy-covariance (EC) system was used to continuously measure the carbon, water, and energy fluxes in a poplar plantation during the growing season (i.e., April–October) over the period 2006–2008 in the Daxing District of Beijing, China. We examined the seasonal and inter-annual variability of gross ecosystem productivity (GEP), net ecosystem exchange (NEE), and ecosystem respiration (ER). Although annual total precipitation was the lowest in 2006, natural rainfall was amended by flood irrigation. In contrast, no supplementary water was provided during a severe drought in spring (i.e., April–June), 2007, resulting in a significant reduction in net ecosystem production (NEP=−NEE). This resulted from the combined effects of larger decrease in GEP than that in ER. Despite the drought – induced reduction in NEP, the plantation forest was a strong carbon sink accumulating 591±62, 641±71, and 929±75gCm−2year−1 for 2006, 2007, and 2008, respectively. The timing of the drought significantly affected the annual GEP. Severe drought during canopy development induced a lasting reduction in carbon exchange throughout the growing season, while the severe drought at the end of growing season did not significantly reduce carbon uptake. Additionally, irrigation reduced negative drought impacts on carbon sequestration. Overall, this fast growing poplar plantation is a strong carbon sink and is sensitive to the changes in environmental conditions.

Historical perspective on the dust bowl drought in the central United States

Three new 159-year long reconstructions of spring, summer, and growing season precipitation totals were developed for northeastern Kansas and northwestern Missouri from five station clusters (Lawrence, Leavenworth, and Manhattan, Kansas; Miami and Oregon, Missouri). Nonstandard observation practices are inherent in the early meteorological data, which can induce an undercount in precipitation measurements, particularly during the cool season. Threshold analyses of these five station clusters indicated undercount can be lessened for daily precipitation totals of 0.50 in. and greater during the warm season (“half-inch threshold”). Therefore, “adjusted reconstructions” of total precipitation for the spring (AMJ), summer (JA), and growing season (AMJJA) were derived using the “half-inch threshold” totals and an estimate of the missing amount between 0.00 and 0.50 in. based on an average of the modern observations at each station (or the nearest available station). The new precipitation reconstructions suggest that the most severe spring drought may have occurred during the mid-19th century, although the potential for undercount is likely highest during the spring season. The most severe summer precipitation deficit is estimated during the 1930s Dust Bowl drought, followed by the summer drought of the 1910s. When precipitation is totaled for the entire growing season, the mid-19th century and Dust Bowl droughts were of approximately equal magnitude and duration in this reconstruction. However, the integration of precipitation and temperature into seasonal measures of effective moisture, using a new 19th century temperature reconstruction for northeastern Kansas, indicates that the 1930s growing season moisture deficit was the most severe and sustained since 1855, highlighting the extraordinarily high temperatures recorded during the 1930s Dust Bowl drought.

Roller Type and Operating Speed Effects on Rye Termination Rates, Soil Moisture, and Yield of Sweet Corn in a No-till System

A field experiment was conducted in Cullman, AL, to evaluate the effects of three different rollers/crimpers on the termination of a rye (Secale cereale L) winter cover crop, soil moisture, and yield of sweet corn (Zea mays saccharata L.) in a no-till system. The following roller types were tested: a straight bar roller, a smooth roller with crimper, and a two-stage roller. These rollers were tested at operating speeds of 3.2 km·h−1 and 6.4 km·h−1. The three rollers/crimpers were compared with a smooth drum roller (no crimping bars) plus glyphosate applied at rate 1.0 kg·ha−1 used as a control. Rye termination dates were selected to be 3 weeks before the recommended sweet corn planting date, which is in the beginning of May for this region. Data indicate that at 3 weeks after rolling for all seasons (2006–2008), 100% rye termination was reached with the smooth drum roller and glyphosate. Two weeks after rolling, average rye termination rates by rollers/crimpers alone were 54.6%, 30.0%, and 50.4% in 2006, 2007, and 2008, respectively. Three weeks after rolling, rye termination rates increased only by ≈10% compared with 2 weeks after rolling. These termination levels were below the recommended rate of 90% termination necessary for planting a cash crop into the cover residue. Lower rye termination was probably caused by rolling the rye in an early growth stage (flowering stage). The rollers’ operating speed did not influence rye termination rates. Similarly, roller type did not affect soil moisture during the first and second week after rolling. Applying glyphosate with rolling did not increase yield of sweet corn in any of the three growing seasons, and in 2006, sweet corn yield was lower compared with the roller alone treatments. These results are important to vegetable organic systems, in which use of herbicides is not allowed. No significant difference in sweet corn yield was found between operating speeds of 3.2 km·h−1 vs. 6.4 km·h−1 and between the assigned treatments in all growing seasons. However, significant differences in sweet corn yield were detected between the years, most likely as a result of different weather patterns. The lowest sweet corn yield of 3513 kg·ha−1 was reported in 2007 as a result of severe drought in spring and summer of 2007. The highest yield of 15,613 kg·ha−1 was recorded in 2006. In 2008, the yield was 10,158 kg·ha−1. Although the different roller designs were not as effective in ending the rye cover crop compared with the glyphosate treatment, sweet corn yields were unaffected. Multiple rolling operations over the same area could be useful if greater rye termination levels are required without the use of a herbicide, but this recommendation should be tested experimentally in more detail.

Effects of spring drought on carbon sequestration, evapotranspiration and water use efficiency in the songnen meadow steppe in northeast China

AbstractGlobal climate change projections suggest an increasing frequency of droughts and extreme rain events in the steppes of the Eurasian region. Using the eddy covariance method, we measured carbon and water balances of a meadow steppe ecosystem in Northeast China during 2 years which had contrasting precipitation patterns in spring seasons in 2007 and 2008. The meadow steppe sequestrated only 64·2 gC m−2 year−1 in 2007 compared to 160·5 gC m−2 year−1 in 2008, due to a severe spring drought in 2007. The 2007 spring drought resulted in a dramatic reduction of leaf area index (LAI) and aboveground net primary productivity (ANPP). However, the meadow steppe still acted as a carbon sink in 2007. The strength of the sink was much greater than that in the typical steppes in Central Mongolia and Inner Mongolia. Spring drought also caused a reduction of plant transpiration (Tr) and total ecosystem evapotranspiration (ET). However, the suppression of ET in 2007 was relatively small in comparison to gross ecosystem productivity (GEP) reduction. Thus, ecosystem water use efficiency (WEU) (GEP/ET) in 2007 was reduced to 5·0 gCO2 kg−1 H2O or 75% of that of 2008. We concluded that spring drought detrimentally impacted meadow steppe ecosystem by reducing leaf areas, biomass, GEP, WUE and associated increases in soil evaporation (Es) that might aggravate soil salinization of the Songnen Plain. Copyright © 2011 John Wiley & Sons, Ltd.

Long‐term trend of precipitation and runoff in Korean river basins

AbstractThe spatial and temporal variations of precipitation and runoff for 139 basins in South Korea were investigated for 34 years (1968–2001). The Precipitation‐Runoff Modelling System (PRMS) was selected for the assessment of basin hydrologic response to varying climates and physiology. A non‐parametric Mann–Kendall's test and regression analysis are used to detect trends in annual, seasonal, and monthly precipitation and runoff, while Moran's I is adapted to determine the degree of spatial dependence in runoff trend among the basins. The results indicated that the long‐term trends in annual precipitation and runoff were increased in northern regions and decreased in south‐western regions of the study area during the study period. The non‐parametric Mann–Kendall test showed that spring streamflow was decreasing, while summer streamflow was increasing. April precipitation decreased between 15% and 74% for basins located in south‐western part of the Korean peninsula. June precipitation increased between 18% and 180% for the majority of the basins. Trends in seasonal and monthly streamflow show similar patterns compared to trends in precipitation. Decreases in spring runoff are associated with decreases in spring precipitation which, accompanied by rising temperatures, are responsible for reducing soil moisture. The regional patterns of precipitation and runoff changes show a strong to moderate positive spatial autocorrelation, suggesting that there is a high potential for severe spring drought and summer flooding in some parts of Korea if these trends continue in the future. Copyright © 2008 John Wiley & Sons, Ltd.

Can Abundant Summer Precipitation Counter Losses in Herbage Production Caused by Spring Drought?

Drought is an inherent trait of most rangelands and sound management necessitates managers address two fundamental questions when facing a drought situation. The first question is, ‘‘what is the probability that a useful amount of precipitation will be received over the period of concern?’’ and the second question is, ‘‘if it does rain, what will the impact be in terms of quantity and quality of herbage produced?’’ The objective of this study was to address the second question. Our hypothesis was that herbage growth response to above normal summer precipitation (i.e., 23 in July and August) would be limited in the northern Great Plains because of a general absence of productive warm-season species. Study plots were twelve 5 3 10-m nonweighing lysimeters. Treatments were: 1) simulated (i.e., rainout shelter imposed), severe spring drought (i.e., 1 May ‐ 1 July) followed by ambient precipitation thereafter; 2) simulated, severe spring drought followed by ambient precipitation thereafter plus summer irrigation (i.e., July and August); 3) ambient precipitation only; and 4) ambient precipitation plus summer irrigation. Results indicated substantial herbage production can be expected in this region during summer when precipitation is well above average because of the positive growth response of blue grama (Bouteloua gracilis [H.B.K.] Lag. ex Griffiths), the dominant warm-season grass growing in this region. However, results also showed that level of production in the study situation (i.e., spring drought, wet summer) was only about 50% of that attained in a normal (i.e., wet spring/dry summer) year. Moreover, long-term weather data shows the probability of receiving 23 normal precipitation in both July and August (i.e., our irrigation treatments) is , 1%. Thus, although these rangelands possess the capacity to respond favorably to summer precipitation, the low probability of receiving substantial levels of summer precipitation ensures levels of ecological and economic risk remain high.

Can Abundant Summer Precipitation Counter Losses in Herbage Production Caused by Spring Drought?

Drought is an inherent trait of most rangelands and sound management necessitates managers address two fundamental questions when facing a drought situation. The first question is, ‘‘what is the probability that a useful amount of precipitation will be received over the period of concern?’’ and the second question is, ‘‘if it does rain, what will the impact be in terms of quantity and quality of herbage produced?’’ The objective of this study was to address the second question. Our hypothesis was that herbage growth response to above normal summer precipitation (i.e., 23 in July and August) would be limited in the northern Great Plains because of a general absence of productive warm-season species. Study plots were twelve 5 X 10-m non-weighing lysimeters. Treatments were: 1) simulated (i.e., rainout shelter imposed), severe spring drought (i.e., 1 May - 1 July) followed by ambient precipitation thereafter; 2) simulated, severe spring drought followed by ambient precipitation thereafter plus summer irrigation (i.e., July and August); 3) ambient precipitation only; and 4) ambient precipitation plus summer irrigation. Results indicated substantial herbage production can be expected in this region during summer when precipitation is well above average because of the positive growth response of blue grama (Bouteloua gracilis [H.B.K.] Lag. ex Griffiths), the dominant warm-season grass growing in this region. However, results also showed that level of production in the study situation (i.e., spring drought, wet summer) was only about 50% of that attained in a normal (i.e., wet spring/dry summer) year. Moreover, long-term weather data shows the probability of receiving 23 normal precipitation in both July and August (i.e., our irrigation treatments) is < 1%. Thus, although these rangelands possess the capacity to respond favorably to summer precipitation, the low probability of receiving substantial levels of summer precipitation ensures levels of ecological and economic risk remain high.

Near-Ground Remote Sensing of Green Area Index on the Shortgrass Prairie

Drought is an inherent trait of most rangelands and sound management necessitates managers address two fundamental questions when facing a drought situation. The first question is, ‘‘what is the probability that a useful amount of precipitation will be received over the period of concern?’’ and the second question is, ‘‘if it does rain, what will the impact be in terms of quantity and quality of herbage produced?’’ The objective of this study was to address the second question. Our hypothesis was that herbage growth response to above normal summer precipitation (i.e., 23 in July and August) would be limited in the northern Great Plains because of a general absence of productive warm-season species. Study plots were twelve 5 X 10-m non-weighing lysimeters. Treatments were: 1) simulated (i.e., rainout shelter imposed), severe spring drought (i.e., 1 May - 1 July) followed by ambient precipitation thereafter; 2) simulated, severe spring drought followed by ambient precipitation thereafter plus summer irrigation (i.e., July and August); 3) ambient precipitation only; and 4) ambient precipitation plus summer irrigation. Results indicated substantial herbage production can be expected in this region during summer when precipitation is well above average because of the positive growth response of blue grama (Bouteloua gracilis [H.B.K.] Lag. ex Griffiths), the dominant warm-season grass growing in this region. However, results also showed that level of production in the study situation (i.e., spring drought, wet summer) was only about 50% of that attained in a normal (i.e., wet spring/dry summer) year. Moreover, long-term weather data shows the probability of receiving 23 normal precipitation in both July and August (i.e., our irrigation treatments) is < 1%. Thus, although these rangelands possess the capacity to respond favorably to summer precipitation, the low probability of receiving substantial levels of summer precipitation ensures levels of ecological and economic risk remain high.

Afforestation using micro-catchment water harvesting system with microphytic crust treatment on semi-arid Loess Plateau: A preliminary result

Water harvesting is one of main measures to solve water shortage resulting from less precipitation and erratically seasonal distribution in arid and semi-arid areas. Different types of anti-infiltration treatments including mechanical and chemical to micro-catchment and their runoff efficiencies had been reported. This paper, through 5 years experiment from 1992 to 1996, is aimed at studying the impacts of microcatchment water-harvesting system (MCWHS) with microphytic crust treatment on afforestation on semi-arid Loess Plateau. The results showed that after 3 years of crust inoculation, crust had covered majority of MCWHS and the function of water harvesting had also been demonstrated partially, there were significant difference in soil moisture of shallow soil layer in three typical spring stages between crust cover and control treatments (0.05 level), and about 0.9%–6.04% increase of monthly mean soil moisture within 1m soil layer in spring of late 3 years. The impact of severe spring drought can be alleviated effectively. In the meanwhile, as crust developed on the treated surface, there are significant differences (0.05 level) for tree height (H), diameter at breast height (DBH) and diameter at ground level (DGL) at the end of the study period (1996) with the increases by 22.38%, 17.34%, and 20.49% respectively compared with the control treatment. Microphytic crust, as one of biological infiltration-proof materials, may become the optimized option for revegetation in Chinese Great West Development Strategy due to its self-propagation, non-pollution to water qualities, long use duration and relatively cost effective. Further work should be focused on the selection of endemic crust species and their batch-culture in arid environment.

Variable Effects of Droughts on the Density of a Sea-Trout Salmo trutta Population Over 30 Years

This study shows how a stock-recruitment model can be used to assess the effects of drought on fish survival, using data from a long-term study of a sea-trout population. Droughts were severest in the summers of 1976, 1983, 1984 (also severe spring drought) and 1995, and less severe in summer, but followed by autumn droughts in 1969, 1989 and 1993. The Ricker curvilinear model significantly fit (P < 0.01) the relationship between initial egg density and survivor density for: parr aged 0 + years sampled in late May or early June, and late August or early September; parr aged 1 + years sampled in late May or early June, and late August or early September; spawning females and their total egg production. These analyses provided strong evidence for density-dependent population regulation and also identified extreme outliers, all these being for year-classes affected by the summer droughts. The variable effects of the seven summer droughts were quantified by expressing the difference between each pair of observed and expected values as a percentage (with 95% CL) of the expected value predicted from the Ricker model. The 1969 drought continued with an autumn drought and reduced the density of 1 + parr (1968 year-class), but had no long-term effects on female or egg densities. The 1983, 1984 (plus spring drought) and 1989 droughts reduced 0+ (1983, 1984 and 1989 year-classes) and 1+ (1982. 1983 and 1988 year-classes) parr densities, and led to low densities of returning females and their eggs from the 1982, 1983, 1988 and 1989 year-classes. The 1976 summer drought, and 1993 summer and autumn droughts had little effect on parr densities, but in the long term produced low densities of returning females and their eggs from the 1975 and 1992 year-classes. The 1995 drought reduced 0+ (1995 year-class) and 1 + (1994 year-class) parr densities, but its long-term effects cannot be evaluated until more data are available. Reduced densities of returning females and their eggs were associated with 1+ parr being subjected to droughts; possible reasons for this are discussed, including growth retardation.