Comparison of Methods for Estimating Crop Water Use: Sap Flow, FAO-56 Penman-Monteith, and Weather Parameters

Knowing crop water uptake each day is useful for developing irrigation scheduling. Many technologies have been used to estimate daily crop water use. Sap flow is one of the technologies that measure water flow through the stem of a plant and estimate daily crop water uptake. Sap flow sensor is an effective direct method for measuring crop water use, but it is relatively expensive and requires frequent maintenance. Therefore, alternative methods, such as evapotranspiration based on FAO 56 Penman-Monteith equation and other weather parameters were evaluated to find the correlation with sap flow. In this study, Dynamax Flow 32-1K sap flow system was utilized to monitor potato water use. The results show sap flow has a strong correlation with evapotranspiration (RMSE = 1.34, IA = 0.89, MBE = -0.83), solar radiation (RMSE = 2.25, IA = 0.72, MBE = -1.80), but not with air temperature, relative humidity, wind speed, and vapor pressure. It is worth noting that the R2 between sap flow and relative humidity was 0.55. This study has concluded that daily evapotranspiration and solar radiation can be used as alternative methods to estimate sap flow.

Assessing Crop Water Demand and Deficit for the Growth of Spring Highland Barley in Tibet, China

The aim of this study was to assess the crop water demand and deficit of spring highland barley and discuss suitable irrigation systems for different regions in Tibet, China. Long-term trends in reference crop evapotranspiration and crop water demand were analyzed in different regions, together with crop water demand and deficit of spring highland barley under different precipitation frequencies. Results showed that precipitation trends during growth stages did not benefit the growth of spring highland barley. The crop coefficient of spring highland barley in Tibet was 0.87 and crop water demand was 389.0 ram. In general, a water deficit was found in Tibet, because precipitation was lower than water consumption of spring highland barley. The most severe water deficit were in the jointing to heading stage and the heading to wax ripeness stage, which are the most important growth stages for spring highland barley; water deficit in these two stages would be harmful to the yield. Water deficit showed different characteristics in different regions. In conclusion, irrigation systems may be more successful if based on an analysis of water deficit within different growth stages and in different regions.

Crop water requirements of major crops indryland of northern China

The concept of crop water requirements is discussed, based on which the calculation modelof crop water requirements is established. In light with crop, soil and meteorological data. the cropwater requirements of major crops in sub-humid and send-arid dryland farming areas of northernChina. including wheat maize , cotton. millet, soybean, sweet potato and potato, are calculated, andthe patterns of crop water requirements of these crops are revealed and discussed in this paper.

Spatiotemporal variations of evapotranspiration and reference crop water requirement over 1957-2016 in Iran based on CRU TS gridded dataset

Agriculture needs to produce more food to feed the growing population in the 21st century.It makes the reference crop water requirement(WREQ)a major challenge especially in regions with limited water and high water demand.Iran,with large climatic variability,is experiencing a serious water crisis due to limited water resources and inefficient agriculture.In order to overcome the issue of uneven distribution of weather stations,gridded Climatic Research Unit(CRU)data was applied to analyze the changes in potential evapotranspiration(PET),effective precipitation(EFFPRE)and WREQ.Validation of data using in situ observation showed an acceptable performance of CRU in Iran.Changes in PET,EFFPRE and WREQ were analyzed in two 30-a periods 1957-1986 and 1987-2016.Comparing two periods showed an increase in PET and WREQ in regions extended from the southwest to northeast and a decrease in the southeast,more significant in summer and spring.However,EFFPRE decreased in the southeast,northeast,and northwest,especially in winter and spring.Analysis of annual trends revealed an upward trend in PET(14.32 mm/decade)and WREQ(25.50 mm/decade),but a downward trend in EFFPRE(-11.8 mm/decade)over the second period.Changes in PET,EFFPRE and WREQ in winter have the impact on the annual trend.Among climate variables,WREQ showed a significant correlation(r=0.59)with minimum temperature.The increase in WREQ and decrease in EFFPRE would exacerbate the agricultural water crisis in Iran.With all changes in PET and WREQ,immediate actions are needed to address the challenges in agriculture and adapt to the changing climate.

PELIMINARY ANALYSES FOR CROP WATER CONSUMPTION BY USING LYSIMETER

This paper deliberates on the issue of water consumption (evapotranspiration, ET) of three main crops in North China: wheat, corn and bean, which is mainly related to three factors as indicated by the definition of SPAC system. Water consumption was measured on daily and sometimes hourly basis by Lysimeter, which can be adjusted to have the same groundwater level as that in the field, thus the measurement could serve as representative of crop water consumption for adjacent area. The consumption period for three crops has been analyzed and cumulative deviation from the mean of daily evapotranspiration been used to divide the whole growing period into several parts, which are related to but different from the growing periods. The serial correlation coefficients for varied lag time have been calculated to verify that the process of daily ET is not random, and therefore the cumulative daily consumption has been simulated by polynomial method, which gives relative good results. Finally, the effort has been made to investigate the relation of crop yield and water consumption and water use efficiency based on a time series of seven years.

Sentinel-1 Radar Data Assessment to Estimate Crop Water Stress

Water is an important component in agricultural production for both yield quantity and quality. Although all weather conditions are driving factors in the agricultural sector, the precipitation in rainfed agriculture is the most limiting weather parameter. Water deficit may occur continuously over the total growing period or during any particular growth stage of the crop. Optical remote sensing is very useful but, in cloudy days it becomes useless. Radar penetrates the cloud and collects information through the backscattering data. Normalized Difference Vegetation Index (NDVI) was extracted from Landsat 8 satellite data and used to calculate Crop Coefficient (Kc). The FAO-Penman-Monteith equation was used to calculate reference evapotranspiration (ETo). NDVI and Land Surface Temperature (LST) were calculated from satellite data and integrated with air temperature measurements to estimate Crop Water Stress Index (CWSI). Then, both CWSI and potential crop evapotranspiration (ETc) were used to calculate actual evapotranspiration (ETa). Sentinel-1 radar data were calibrated using SNAP software. The relation between backscattering (dB) and CWSI was an inverse relationship and R2 was as high as 0.82.

Spectral Crop Coefficient Approach for Estimating Daily Crop Water Use

While the amount of water used by a crop can be measured using lysimeters or eddy covariance systems, it is more common to estimate this quantity based on weather data and crop-related factors. Among these approaches, the standard crop coefficient method has gained widespread use. A limitation of the standard crop coefficient approach is that it applies to “standard conditions” that are invariant from field to field. In this article, we describe a method for estimating daily crop water use (CWU) that is specific to individual fields. This method, the “spectral crop coefficient” approach, utilizes a crop coefficient numerically equivalent to the crop ground cover observed in a field using remote sensing. This “spectral crop coefficient” Ksp is multiplied by potential evapotranspiration determined from standard weather observations to estimate CWU. We present results from a study involving three farmers' fields in the Texas High Plains in which CWU estimated using the Ksp approach is compared to observed values obtained from eddy covariance measurements. Statistical analysis of the results suggests that the Ksp approach can produce reasonably accurate estimates of daily CWU under a variety of irrigation strategies from fully irrigated to dryland. These results suggest that the Ksp?approach could be effectively used in applications such as operational irrigation scheduling, where its field-specific nature could minimize over-irrigation and support water conservation.

The influences of canopy temperature measuring on the derived crop water stress index

Crop water stress index(CWSI)is widely used for efficient irrigation management.Precise canopy temperature(T_(c))measurement is necessary to derive a reliable CWSI.The objective of this research was to investigate the influences of atmospheric conditions,settled height,view angle of infrared thermography,and investigating time of temperature measuring on the performance of the CWSI.Three irrigation treatments were used to create different soil water conditions during the 2020-2021 and 2021-2022 winter wheat-growing seasons.The CWSI was calculated using the CWSI-E(an empirical approach)and CWSI-T(a theoretical approach)based on the T_(c).Weather conditions were recorded continuously throughout the experimental period.The results showed that atmospheric conditions influenced the estimation of the CWSI;when the vapor pressure deficit(VPD)was>2000 Pa,the estimated CWSI was related to soil water conditions.The height of the installed infrared thermograph influenced the T_(c)values,and the differences among the T_(c)values measured at height of 3,5,and 10 m was smaller in the afternoon than in the morning.However,the lens of the thermometer facing south recorded a higher T_(c)than those facing east or north,especially at a low height,indicating that the direction of the thermometer had a significant influence on T_(c).There was a large variation in CWSI derived at different times of the day,and the midday measurements(12:00-15:00)were the most reliable for estimating CWSI.Negative linear relationships were found between the transpiration rate and CWSI-E(R^(2)of 0.3646-0.5725)and CWSI-T(R^(2)of 0.5407-0.7213).The relations between fraction of available soil water(FASW)with CWSI-T was higher than that with CWSI-E,indicating CWSI-T was more accurate for predicting crop water status.In addition,The R^(2)between CWSI-T and FASW at 14:00 was higher than that at other times,indicating that 14:00 was the optimal time for using the CWSI for crop water status monitoring.Relative higher yield of winter wheat was obtained with average seasonal values of CWSI-E and CWSI-T around 0.23 and 0.25-0.26,respectively.The CWSI-E values were more easily influenced by meteorological factors and the timing of the measurements,and using the theoretical approach to derive the CWSI was recommended for precise irrigation water management.

Evaluation of Actual Evapotranspiration and Crop Coefficient in Carrot by Remote Sensing Methodology Using Drainage and River Water to Overcome Reduced Water Availability

Searching for alternative methods for traditional irrigation is World trend at days due to a reduction in water and increased of drought due to climate changes therefore farmers need use modern methods of scheduling water and minimizing water losses while also increasing yield. To meet the future increasing demands water and food there is a need to utilize alternative methods to reduce evaporation, transpiration and deep percolation of water. Any countries use recycled water (drain and sewage) and desalination water from the sea or drains to irrigate crops plus computing actual crop evapotranspiration (ETc) so as to calculate the amount of water to apply to a crop. The paper aims to assess the actual evaporation and evaporation coefficient of carrots, by planting carrots in a field and the crop was exposed to several sources of water (DW and RW) and comparing ETc, Kc and production among plots of three sites (A, B and C). The study used two types of irrigation water (drain water (DW) and river water (RW)). The results were to monthly rate and accumulated actual evapotranspiration to C (irrigation by RW only) more than A (67% RW and 33% DW) and B (17% RW and 83% DW) via 7% and 58%, respectively. The yield to C more than A and B by 17% and 75%, respectively. In conclusion the use of DW can cause a reduction in crop consumptive of carrot crops also causes a reduction in yield, crop length, root length, root size, canopy of crop, number of leaves and biomass of the plant therefore, the drainage water needs to treated before irrigating crops And making use of it to irrigate the fields and fill the shortfall in the amount of water from the river. The drain water helped on filling the water shortage due to climate changes and giving production of carrot crop but less than river water.

Field water surplus and deficit of major crops in dryland of northern China

The definition and classification of field evapotranspiration was discussed, based on which the calculation model for field evapotranspiration was established. Based on crop, soil measurements and mean climatic data in 1950-1980, mean field water surplus or deficit on climatic, crop and cropland basis in dryland of northern China was calculated, and the pattern of field water surplus or deficit was analyzed and discussed in this paper.

Impacts of Recent Climate Change on Dry-Land Crop Water Consumption in the Northern Agro-Pastoral Transitional Zone of China

Climate change has substantially impacted crop growth and development in the northern agro-pastoral transitional zone. Examination of the response of crop water consumption to climate change may provide a guide for adapting local agricultural production and ecological construction to new realities. The water consumption of three local crops （wheat, naked oats, and potatoes） is examined for Wuchuan County in the northern agro-pastoral transitional zone of China using meteorological data from 1960 to 2007 and soil moisture data from 1983 to 2007. The relationships between climate change and the crop water consumption are discussed. The results show that Wuchuan experienced both a warming trend and a reduction of precipitation between 1960 and 2007. The annual mean surface air temperature increased at a rate of 0.04℃ yr-1 and the annual precipitation decreased at a rate of 0.7 mm yr-1 . Both trends are particularly pronounced between 1983 and 2007, with an increase in annual mean temperature of 0.09℃ yr-1 and a decrease in annual mean precipitation of 2.1 mm yr-1 . Crop water consumption decreased between 1983 and 2007 for wheat （1.65 mm yr-1 ）, naked oats （2.04 mm yr-1 ）, and potatoes （3.85 mm yr-1 ）. Potatoes and naked oats consume more water than wheat. Climate change has significantly impacted crop water consumption. Water consumption and rainfall during the growing season are positively correlated, while water consumption and active accumulated temperature are negatively correlated. Compared to precipitation, accumulated temperature has little impact on crop water consumption. Recent climate change has been detrimental for crop production in Wuchuan County. Adaptation to climate change should include efforts to breed drought-resistant crops and to develop drought-resistant cultivation techniques.

Real-time remote monitoring system for crop water requirement information

Rapidly acquiring and real-time transmitting crop water requirement information constitute the basis for achieving intelligent diagnosis and precision irrigation.In order to collect and transmit crop water requirement information at real time,a new microcontroller-based real-time remote monitoring system was designed,including system hardware design,software and anti-jamming design.The system achieved the functions including clock reading,information configuration,LCD display,keyboard control,data sending and receiving,multi-channel information acquisition,conversion and storage.Laboratory and field tests showed that the system can achieve data acquisition and real-time display of the crop water requirement information.Unlike the current weather station,the system collects crop water information,meteorological factors and soil parameters at the same time.It has a high level of stability and acquisition accuracy,and can meet the requirements for real-time remote monitoring of the crop water requirement information for irrigation decision-making.

Crop water stress index for off-season greenhouse green peppers in Liaoning, China

The crop water stress index(CWSI)is a complex instrument to effectively monitor the degree of water stress of crops and provides guidance for timely irrigation.In an experiment utilizing the CWSI with off-season green peppers planted in barrels in a greenhouse in Liaoning Province,Northeast China,this study monitors the sub-indexes--such as canopy temperature,environmental factors and yield--determines the changing law of each constituent,achieves an empirical model as well as a baseline formula for the canopy temperature of the peppers with a sufficient water supply,and verifies the rationality of the formula with corresponding experimental data.The results obtained by using the CWSI show that the optimal time to determine the water deficit for off-season green peppers is at noon,by measuring the diurnal variation in the peppers with different water supplies.There is a nonlinear relationship between the yield and the average CWSI at the prime fruit-bearing period;moreover,the optimal time to supply water for off-season green peppers comes when the average water stress index ranges between 0.2 and 0.4 during the prime fruiting stage,thereby ensuring a high yield.

A meta-analysis of global crop water productivity of three leading world crops(wheat,corn,and rice)in the irrigated areas over three decades

The overarching goal of this study was to perform a comprehensive metaanalysis of irrigated agricultural Crop Water Productivity(CWP)of the world’s three leading crops:wheat,corn,and rice based on three decades of remote sensing and non-remote sensing-based studies.Overall,CWP data from 148 crop growing study sites(60 wheat,43 corn,and 45 rice)spread across the world were gathered from published articles spanning 31 different countries.There was overwhelming evidence of a significant increase in CWP with an increase in latitude for predominately northern hemisphere datasets.For example,corn grown in latitude 40–50°had much higher mean CWP(2.45 kg/m^(3))compared to mean CWP of corn grown in other latitudes such as 30–40°(1.67 kg/m^(3))or 20–30°(0.94 kg/m^(3)).The same trend existed for wheat and rice as well.For soils,none of the CWP values,for any of the three crops,were statistically different.However,mean CWP in higher latitudes for the same soil was significantly higher than the mean CWP for the same soil in lower latitudes.This applied for all three crops studied.For wheat,the global CWP categories were low(≤0.75 kg/m^(3)),medium(>0.75 to<1.10 kg/m^(3)),and high CWP(≥1.10 kg/m^(3)).For corn the global CWP categories were low(≤1.25 kg/m^(3)),medium(>1.25 to≤1.75 kg/m^(3)),and high(>1.75 kg/m^(3)).For rice the global CWP categories were low(≤0.70 kg/m^(3)),medium(>0.70 to≤1.25 kg/m^(3)),and high(>1.25 kg/m^(3)).USA and China are the only two countries that have consistently high CWP for wheat,corn,and rice.Australia and India have medium CWP for wheat and rice.India’s corn,however,has low CWP.Egypt,Turkey,Netherlands,Mexico,and Israel have high CWP for wheat.Romania,Argentina,and Hungary have high CWP for corn,and Philippines has high CWP for rice.All other countries have either low or medium CWP for all three crops.Based on data in this study,the highest consumers of water for crop production also have the most potential for water savings.These countries are USA,India,and China for wheat;USA,China,and Brazil for corn;India,China,and Pakistan for rice.For example,even just a 10%increase in CWP of wheat grown in India can save 6974 billion liters of water.This is equivalent to creating 6974 lakes each of 100 m^(3)in volume that leads to many benefits such as acting as‘water banks’for lean season,recreation,and numerous ecological services.This study establishes the volume of water that can be saved for each crop in each country when there is an increase in CWP by 10%,20%,and 30%.

Remote sensing monitoring on regional crop water productivity in the Haihe River Basin

Crop water productivity （CWP） agricultural development in water scarcity is one of the important indicators for sustainable area. There is serious conflict between water sup- ply and requirement in the Haihe River Basin. CWP of winter wheat and summer maize from 2003 to 2007 in the Haihe River Basin is estimated based on large-scale evapotranspiration （ET） and crop yield obtained by remote sensing technology. Spatial and temporal distribution of CWP of winter wheat and summer maize is investigated in this study. Results show that CWP of winter wheat in most parts of the study area varies from 1.02 kg/m3 to 1.53 kg/m3, and CWP of summer maize varies from 1.31 kg/m3 to 2.03 kg/m3. Multi-year averaged CWP of winter wheat and summer maize in the study area is about 1.19 kg/m3 and 1.59 kg/m3. CWP results show certain promotion potential to alleviate the water shortage in the Haihe River Basin. Correlation analysis of CWP, crop yield and ET shows that there is great potential for crop yield promotion without the growth in irrigation water. Large-scale CWP estimated by remote sensing technology in this study shows spatial distribution features, which could be used to real-time agricultural water resource management combined with crop yield and ET.

Investigation of crop evapotranspiration and irrigation water requirement in the lower Amu Darya River Basin, Central Asia

High water consumption and inefficient irrigation management in the agriculture sector of the middle and lower reaches of the Amu Darya River Basin(ADRB)have significantly influenced the gradual shrinking of the Aral Sea and its ecosystem.In this study,we investigated the crop water consumption in the growing seasons and the irrigation water requirement for different crop types in the lower ADRB during 2004–2017.We applied the FAO Penman–Monteith method to estimate reference evapotranspiration(ET0)based on daily climatic data collected from four meteorological stations.Crop evapotranspiration(ETc)of specific crop types was calculated by the crop coefficient.Then,we analyzed the net irrigation requirement(NIR)based on the effective precipitation with crop water requirements.The results indicated that the lowest monthly ET0 values in the lower ADRB were found in December(18.2 mm)and January(16.0 mm),and the highest monthly ET0 values were found in June and July,with similar values of 211.6 mm.The annual ETc reached to 887.2,1002.1,and 492.0 mm for cotton,rice,and wheat,respectively.The average regional NIR ranged from 514.9 to 715.0 mm in the 10 Irrigation System Management Organizations(UISs)in the study area,while the total required irrigation volume for the whole region ranged from 4.2×109 to 11.6×109 m3 during 2004–2017.The percentages of NIR in SIW(surface irrigation water)ranged from 46.4%to 65.2%during the study period,with the exceptions of the drought years of 2008 and 2011,in which there was a significantly less runoff in the Amu Darya River.This study provides an overview for local water authorities to achieve optimal regional water allocation in the study area.

Effect of future climate change on the water footprint of major crops in southern Tajikistan

Danghara,a major food production area in southern Tajikistan,is currently suffering from the impact of rapid climate change and intensive human activities.Assessing the future impact of climate change on crop water requirements(CWRs)for the current growing period and defining the optimal sowing date to reduce future crop water demand are essential for local/regional water and food planning.Therefore,this study attempted to analyze possible future climate change effects on the water requirements of major crops using the statistical downscaling method in the Danghara District to simulate the future temperature and precipitation for two future periods(2021-2050 and 2051-2080),under three representative concentration pathways(RCP2.6,RCP4.5,and RCP8.5)according to the CanESM2 global climate model.The water footprint(WFP)of major crops was calculated as a measure of their CWRs.The increased projection of precipitation and temperature probably caused an increase in the main crop’s WFP for the current growing period,which was mainly due to the green water(GW)component in the long term and a decrease in the blue water(BW)component during the second future period,except for cotton,where all components were predicted to remain stable.Under three scenarios for the two future potato and winter wheat decreased from 5.7%to 4.8%and 3.4%to 2.2%,respectively.Although the WFP of cotton demonstrated a stable increase,according to the optimal sowing date,adecrease in irrigation demand or Bw was expected.The results of our study might be useful fordeveloping a new strategy related to irrigation systems and could help to find a balance betweenwater and food for environmental water demands and human use.

An Integrated Framework for Regional Assessment of Water, Energy, and Nutrients from Food Loss of Selected Crops in the Lower Fraser Valley, Canada

Although there is no global shortage of food or water, food security has not been achieved, as human activity has turned these vital resources into “waste”. Wasted food not only loses valuable water resources but embedded calories of human energy and nutrients for healthy human populations. The Food and Agricultural Organization of the United Nations, in addressing these concerns, focuses on a global scale largely on an economic estimate of individual components of energy or water or nutrient loss. It is suggested that more information is required through local or regional assessments to provide better estimates, incorporating regional factors of the losses along the food supply chain. To address this suggestion, this study focused on an intensive agricultural and rapidly urbanizing region of Canada, the Lower Fraser Valley of British Columbia. Seven selected crops, including annual crops such as green peas, sweet corn and potato, and perennial crops that included three berry crops were assessed for their water, both constituent and virtual, as well as embedded energy, protein, and Vitamin C. Annual virtual water losses were higher for sprinkler than drip irrigation, ranging from 82 × 106 kg of water for strawberry to 7570 × 106 kg for blueberry. These high virtual water losses estimated along the food chain confirm the significance of food loss impacts on local water resources. Estimates of losses of food in kg were highest at the consumer level along the food chain and it was estimated that wasted food from the seven crops selected would have supplied the protein and caloric energy of over 33,000 men per year and Vitamin C of about 240,000 men per year. This assessment increases the awareness of food loss impacts from a regional perspective and provides a framework for future research on both environmental and nutritional implications of wasted food.

Implications of future climate change on crop and irrigation water requirements in a semi-arid river basin using CMIP6 GCMs

Agriculture faces risks due to increasing stress from climate change,particularly in semi-arid regions.Lack of understanding of crop water requirement(CWR)and irrigation water requirement(IWR)in a changing climate may result in crop failure and socioeconomic problems that can become detrimental to agriculture-based economies in emerging nations worldwide.Previous research in CWR and IWR has largely focused on large river basins and scenarios from the Coupled Model Intercomparison Project Phase 3(CMIP3)and Coupled Model Intercomparison Project Phase 5(CMIP5)to account for the impacts of climate change on crops.Smaller basins,however,are more susceptible to regional climate change,with more significant impacts on crops.This study estimates CWRs and IWRs for five crops(sugarcane,wheat,cotton,sorghum,and soybean)in the Pravara River Basin(area of 6537 km^(2))of India using outputs from the most recent Coupled Model Intercomparison Project Phase 6(CMIP6)General Circulation Models(GCMs)under Shared Socio-economic Pathway(SSP)245 and SSP585 scenarios.An increase in mean annual rainfall is projected under both scenarios in the 2050s and 2080s using ten selected CMIP6 GCMs.CWRs for all crops may decline in almost all of the CMIP6 GCMs in the 2050s and 2080s(with the exceptions of ACCESS-CM-2 and ACCESS-ESM-1.5)under SSP245 and SSP585 scenarios.The availability of increasing soil moisture in the root zone due to increasing rainfall and a decrease in the projected maximum temperature may be responsible for this decline in CWR.Similarly,except for soybean and cotton,the projected IWRs for all other three crops under SSP245 and SSP585 scenarios show a decrease or a small increase in the 2050s and 2080s in most CMIP6 GCMs.These findings are important for agricultural researchers and water resource managers to implement long-term crop planning techniques and to reduce the negative impacts of climate change and associated rainfall variability to avert crop failure and agricultural losses.

LINKING CROP WATER PRODUCTIVITY TO SOIL PHYSICAL,CHEMICAL AND MICROBIAL PROPERTIES

Agriculture uses a large proportion of global and regional water resources.Due to the rapid increase of population in the world,the increasing competition for water resources has led to an urgent need in increasing crop water productivity for agricultural sustainability.As the medium for crop growth,soils and their properties are important in affecting crop water productivity.This review examines the effects of soil physical,chemical,and microbial properties on crop water productivity and the quantitative relationships between them.A comprehensive view of these relationships may provide important insights for soil and water management in arable land for agriculture in the future.