Irrigation Events Research Articles

Tomato productivity and soil greenhouse gas emissions under reduced water and N fertilizers in a Mediterranean environment

Individuating strategies to reduce greenhouse gas (GHG) emissions from agricultural soil, while preserving crop yield and the quality of products is needed. The major GHG emitted from agricultural soils is nitrous oxide (N2O) and its production is largely influenced by the amount of nitrogen (N) fertilizers applied and by the soil conditions, such as water content and temperature. The cultivation of processing tomato may lead to high N losses because it is characterized by a high frequency of irrigation events and N fertilizer applications. In this study we assessed the effect of reducing water from reintegration of 100% of water missing to field capacity (Ir2) to 50% (Ir1) and N applied, by 30% from 170 kg N ha-1 (N2) to 120 kg N ha-1 (N1) and 100% from N2 to 0 kg N ha-1 (N0), on yield, fruit quality and GHG emissions from soil in tomato cultivated under fertigation for two growing seasons (2014, 2015). We highlighted a great variability of results, both on GHG emissions from soil and on tomato productivity, due to differences in meteorological conditions in the two growing seasons. Higher marketable yield of tomato was recorded in N2 than in N1 only in 2014 and in Ir2 than Ir1 only in 2015, while reducing the agricultural inputs did not reduce the fruit quality. Carbon dioxide and nitrous oxide emissions were higher in 2015, while soil was a sink for methane in both growing seasons. We highlighted a general trend in lower nitrous oxide emissions with reduced water and N fertilizer rate, even if these emissions were largely variable in time and space. In particular, yield-scaled N2O emissions were lower in Ir1 than in Ir2, suggesting that a reduction of the irrigation level may be a suitable strategy for mitigating N2O emissions from tomato cultivated under fertigation in a Mediterranean environment.

Two irrigation events can achieve relatively high, stable corn yield and water productivity in aeolian sandy soil of northeast China

To achieve relatively high, stable corn (Zea mays L.) yield and water productivity (WPc) in aeolian sandy soil in the corn belt of northeast China (CBNC), a 4-year field experiment was conducted from 2017 to 2020 to evaluate the effects of irrigation on yield and WPc. The field experiment included four treatments: no irrigation (NI), single irrigation (SI), two irrigation events (TI), and full irrigation (FI) at the Lishu Experimental Station, Jilin Province, China. The results showed that, the TI and FI treatments improved the relative soil water content (RSWC) of the corn root zone and the aboveground biomass relative to the NI and SI treatments. The corn yield in the SI, TI, and FI treatments was 16–187%, 19–438%, and 17–409% greater than that of the NI treatment, respectively. The coefficient of variation of yield from 2017 to 2020 in the NI, SI, TI, and FI treatments were 47%, 23%, 4%, and 2%, respectively. The TI and FI treatments increased evapotranspiration relative to the NI and SI treatments. The TI and FI treatments increased the WPc by 10–396% and 24–324% compared with the NI treatment. No difference in WPc was observed between the TI and FI treatments. The irrigation water productivity (WPI) of the TI treatment was 35% and 46% higher than that of the FI treatment in 2017 and 2020, respectively, while no difference was observed in 2018 and 2019. Therefore, the TI treatment is recommended to improve the yield and WPc of corn in the aeolian sandy soil of the CBNC.

Impact of imposed root lodging on corn growth and yield

AbstractStrong winds combined with heavy rains can push corn (Zea mays L.) plants over and pull roots part way out of the soil. Weather events that bring these conditions are becoming more frequent in occurrence in the midwestern United States. Yield losses due to root lodging have been related to partial loss of root activity and reduced light interception, but also may stem from affected pollination and kernel fill. A field study was conducted in Ohio from 2018 to 2020 that simulated root lodging from strong winds imposed at V10, V13–14, VT–R1, or R3 growth stages in three modern hybrids. Plants were pushed perpendicular to row direction at the specified stage following natural rain or irrigation events. Differences in hybrids were recorded in this study, but each hybrid exhibited a similar response to lodging (hybrid × lodging interaction was not evident). Yield was reduced by 5, 22, 43, and 33% compared to non‐lodged control at V10, V13–14, VT–R1, and R3, respectively. Light interception in the upper canopy decreased when measured at R4 if lodged previously, and was of greater magnitude as lodging occurred later in the season. Poor pollination contributed to the large yield loss at VT–R1. In addition to reduced yield, increased vivipary and decreased kernel weights in the R3 treatments could further reduce grain quality. These yield losses from this study are greater than have been reported previously, and should be considered when assessing fields for severe wind damage in the future.

Unimodal response of N2O flux to changing rainfall amount and frequency in a wet meadow in the Tibetan Plateau

The rainfall amount and the frequency of extreme rainfall events have been predicted to increase in the Qinghai-Tibetan Plateau during the growing season. These changes will likely affect ecosystem processes, including those that control nitrogen (N) cycling and storage; however, the direction of the changes remains unclear. In this study, we experimentally altered the amount and frequency of precipitation events during the growing season (May through October) at an alpine wetland in the Qinghai-Tibetan Plateau. The treatments included ambient rain (CK) plus 25 mm of extra water for each irrigation event but with different irrigation frequency, i.e., weekly (DF1), biweekly (DF2), every three weeks (DF3) and every four weeks (DF4). During the growing season, the N2O flux showed a large seasonal variation. Compared with the treatment of natural rainfall events, the increase in the rainfall amount promoted the N2O emission flux. As the frequency of rainfall events increased, the aboveground biomass increased significantly from 85.82 g·m−2 to 245.79 g·m−2, and the accumulated N2O emissions first increased and then decreased; we observed the peak of the N2O flux at the DF2 rainfall frequency. We also found the significant linear relationships between soil N2O flux, nitrate nitrogen, and microbial biomass nitrogen content. Furthermore, among the soil microbial factors, higher rainfall frequency (DF1) significantly reduced the relative abundance of the original dominant species (Alphaproteobacteria) in the studied wetland soil. Our results indicate that alpine wetlands are highly sensitive to increased precipitation variability and high frequencies of extreme rainfall events could significantly reduce N2O emission. Future precipitation patterns could weaken the contribution rate of wetland N2O emission to the global warming.

Proximal Gamma-Ray Spectroscopy: An Effective Tool to Discern Rain from Irrigation

Proximal gamma-ray spectroscopy is a consolidated technology for a continuous and real-time tracing of soil water content at field scale. New developments have shown that this method can also act as an unbiased tool for remotely distinguishing rainwater from irrigation without any meteorological support information. Given a single detector, the simultaneous observation in a gamma spectrum of a transient increase in the 214Pb signal, coupled with a decrease in the 40K signal, acts as an effective proxy for rainfall. A decrease in both 214Pb and 40K signals is, instead, a reliable fingerprint for irrigation. We successfully proved this rationale in two data-taking campaigns performed on an agricultural test field with different crop types (tomato and maize). The soil moisture levels were assessed via the 40K gamma signal on the basis of a one-time setup calibration. The validation against a set of gravimetric measurements showed excellent results on both bare and vegetated soil conditions. Simultaneously, the observed rain-induced increase in the 214Pb signal permitted to identify accurately the rain and irrigation events occurred in the 8852 h of data taking.

Technical note: Evaporating water is different from bulk soil water in <i>δ</i><sup>2</sup>H and <i>δ</i><sup>18</sup>O and has implications for evaporation calculation

Abstract. Soil evaporation is a key process in the water cycle and can be conveniently quantified using δ2H and δ18O in bulk surface soil water (BW). However, recent research shows that soil water in larger pores evaporates first and differs from water in smaller pores in δ2H and δ18O, which disqualifies the quantification of evaporation from BW δ2H and δ18O. We hypothesized that BW had different isotopic compositions from evaporating water (EW). Therefore, our objectives were to test this hypothesis first and then evaluate whether the isotopic difference alters the calculated evaporative water loss. We measured the isotopic composition of soil water during two continuous evaporation periods in a summer maize field. Period I had a duration of 32 d, following a natural precipitation event, and period II lasted 24 d, following an irrigation event with a 2H-enriched water. BW was obtained by cryogenically extracting water from samples of 0–5 cm soil taken every 3 d; EW was derived from condensation water collected every 2 d on a plastic film placed on the soil surface. The results showed that when event water was heavier than pre-event BW, δ2H of BW in period II decreased, with an increase in evaporation time, indicating heavy water evaporation. When event water was lighter than the pre-event BW, δ2H and δ18O of BW in period I and δ18O of BW in period II increased with increasing evaporation time, suggesting light water evaporation. Moreover, relative to BW, EW had significantly smaller δ2H and δ18O in period I and significantly smaller δ18O in period II (p<0.05). These observations suggest that the evaporating water was close to the event water, both of which differed from the bulk soil water. Furthermore, the event water might be in larger pores from which evaporation takes precedence. The soil evaporative water losses derived from EW isotopes were compared with those from BW. With a small isotopic difference between EW and BW, the evaporative water losses in the soil did not differ significantly (p>0.05). Our results have important implications for quantifying evaporation processes using water stable isotopes. Future studies are needed to investigate how soil water isotopes partition differently between pores in soils with different pore size distributions and how this might affect soil evaporation estimation.

Soil water-balance-based approach for estimating percolation with lysimeter and in field with and without mulch under micro irrigation

Precise, accurate knowledge of percolation is key to reliable determination of soil water balance and a crop’s water-use efficiency. This work evaluated an approach to estimate the amount of water percolated in the root zone using soil water content (SWC) data measured at different time intervals. The approach was based on the difference of soil water content within and below the effective root zone of banana plants at different time intervals. A drainage lysimeter was used to compare the measured and estimated percolation data. The approach was then used in a banana orchard under drip and micro sprinkler irrigation, with and without the use of mulch. The soil water storage in the banana’s root zone was evaluated within a two-dimensional soil profile with time domain reflectometry (TDR). Mean percolation measured in the lysimeters did not differ from the approach’s estimates using intervals between SWC readings equal to or longer than 6 h from the end of an irrigation event. Percolation estimates under drip and micro sprinkler irrigation in the field, with and without mulch, were consistent with those measured in the lysimeters, considering the 6-h interval of SWC measurements. Percolation was greater under the drip irrigation system with mulch. The amount of water percolated was not influenced by the presence of mulch under the micro sprinkler system.
 Keywords: localized irrigation, soil water balance, soil water content sensor.

A MODEL FOR PREDICTING AND IMPROVING IRRIGATION WATER MANAGEMENT IN EGYPT – CORN as A CASE STUDY

Current And Predicted Irrigation Management (CAPIM) model was designed to predict and improve irrigation water management. Its inputs include daily weather data and the outputs are daily evapotranspiration that could be estimated under current conditions using Penman-Monteith equation (P-M), and under climate change using Hargreaves-Samani equation (H-S); and determine the irrigation timing and the amount of water needed for each irrigation event. The CAPIM model was used to develop irrigation schedule for corn crop at different geographic regions in Egypt as (El-Dakahlia; El-Fayoum and Assuit) under RCP8.5 scenario and MIROC- ESM climate model during 2018s, 2040s, 2080s. The model was also used to determine the best adaptive strategy for conforming to the predicted climate changes. CAPIM results were verified by comparing them with results from two known programs (CropWat-8 and ETo-Estimation). The results show that CAPIM predicted the ETo values under current and predicted climate conditions accurately as the agreement value was 0.99. Gross irrigation results during the projected periods 2040s and 2080s are higher than 2018s in the three selected sites. El- Fayoum Governorate is the highest in terms of the number of irrigations and the percentage of increasing GIR. As GIR increased by 28% in 2080s and 29 % in 2040s with 18 hills totaling (2008 and 2077 mm/season), respectively. Moreover, increasing system efficiency by 5 % or 10 % is the best adaptive strategy as it increases the potential yield by about 9 % and 18 % and the WP by 9.4 % and 18.7 %.

Comparison of POCIS and grab sampling techniques for monitoring PPCPs in vernal pools in central Pennsylvania

Active ingredients in pharmaceuticals and personal care products (PPCPs) can persist through wastewater treatment plants and be released into the environment where they can inadvertently pose risks to non-target organisms. Emerging contaminants (ECs), including PPCPs, are commonly detected in wastewater effluent. With the increasing beneficial re-use of treated wastewater globally, there is a need to understand how spray-irrigation activities affect the occurrence and persistence of ECs in the environment to which they are introduced. Here, we explore the impacts of wastewater spray-irrigation on nearby ephemeral wetlands (e.g., vernal pools) through the use of grab and Polar Organic Chemical Integrative Sampling (POCIS) techniques. This study sought to determine whether integrative sampling techniques are better suited than traditional grab sampling techniques in assessing the presence and concentrations of ECs in vernal pools by evaluating 34 ECs in six vernal pools in central Pennsylvania. Three pools were impacted by wastewater spray-irrigation activities and three were in a nearby forested area. Results of this study found that POCIS detected a wide range of 25 ECs (log Kow between −2.6 and 9.37) more or, in some cases, equally frequently, relative to grab samples. Additionally, grab samples were found to best capture short-lived elevated inputs of ECs (from irrigation events) while POCIS were found to best capture ECs that were present in vernal pools over a longer period of time (weeks to months). For ECs detected more frequently in grab samples, concentrations were higher compared to time weighted average aqueous concentrations estimated from POCIS. This study advances understanding of the potential impact of wastewater beneficial reuse on vernal pools and informs how best to monitor the presence of ECs in vernal pools using integrative and grab sampling techniques.

Detecting crop water requirement indicators in irrigated agroecosystems from soil water content profiles: An application for a citrus orchard

Most perennial crops sensitive to water scarcity, such as citrus, can benefit from efficient water management, which allows for reduced water consumption while increasing crop production on a long-term basis. However, when implementing water-saving strategies, it is necessary to monitor soil and/or plant water status in order to determine crop water demand. A plethora of devices providing indirect measurements of volumetric soil water content, such as the “drill and drop” multi-sensors probes (Sentek, Inc., Stepney, Australia), have been developed over the last decade.The objective of the paper was to analyse time-series of soil water content profiles and meteorological data collected in an adult citrus orchard over three years of field observations (2017–2020) in order to estimate actual crop evapotranspiration and derive crop coefficients. Simultaneous measurements of sap fluxes also allowed for the estimation of the basal crop coefficient, Kcb, used as a control variable.The temporal dynamics of soil water content profiles following rainfall or irrigation events provided information on soil evaporation, root water uptake, and actual crop transpiration. After soil wetting events, in particular, it was possible to recognize patterns of actual crop evapotranspiration similar to those detected with sap flow sensors. The knowledge of actual crop evapotranspiration at the daily time-step, in conjunction with the corresponding reference crop evapotranspiration, allowed for appropriate estimations of the crop coefficient associated with the various development stages. The proposed method provided interesting insights into the dynamics of root water uptake and crop evapotranspiration of the studied citrus orchard, and it represents a promising tool for precise irrigation scheduling in other agroecosystems.

Preferential flow under high‐intensity short‐duration irrigation events in soil columns from a karst and nonkarst landscape

AbstractPreferential flow through soil macropores is a major cause of rapid transport of contaminants through soils to drainages systems. Knowledge of the extent of macropore flow in different soil systems is crucial for the effective implementation of nutrient management plans. The objective of this study was to determine the differences in preferential flow in soil columns characterized by varying contents of coarse fragments with depth and obtained from a regional, pasture‐based karst and a nonkarst landscape. Intact soil columns (40 × 100 cm; two replicates per treatment) were subjected to two Brˉ leaching experiments (BL1 and BL2) which included a pulse application of Brˉ tracer solution (3.02 and 1.15 g L−1 during BL1 and BL2, respectively), each followed by five successive irrigation events (5.67 mm min−1 for 2 min in 30‐min intervals). Each soil column rested on a stainless‐steel grid (consisting of 100 cells, each measuring 3.81 cm × 3.81 cm), which facilitated partitioning of the soil bottom and collection of drainage from each grid. Significant differences in the drainage losses of water and Brˉ through the 1‐m‐deep soil profiles were observed with karst‐derived stony soils draining approximately five times greater water and Brˉ, compared with nonkarst‐derived soil. These results suggest that soils with high fraction of coarse fragments are more susceptible to leaching losses than soils with less coarse fragments. Further studies under different flow regimes and encompassing different soil units may be beneficial in understanding the potential leaching risk in these areas and for implementing best management practices for landscape‐based nutrient management.

Survival of Escherichia coli and Listeria innocua on Lettuce after Irrigation with Contaminated Water in a Temperate Climate.

Microbial disease outbreaks related to fresh produce consumption, including leafy green vegetables, have increased in recent years. Where contamination occurs, pathogen persistence may represent a risk for consumers’ health. This study analysed the survival of E. coli and L. innocua on lettuce plants watered with contaminated irrigation water via a single irrigation event and within stored irrigation water. Separate lettuce plants (Lactuca sativa var. capitata) were irrigated with water spiked with Log10 7 cfu/mL of each of the two strains and survival assessed via direct enumeration, enrichment and qPCR. In parallel, individual 20 L water microcosms were spiked with Log10 7 cfu/mL of the individual strains and sampled at similar time points. Both strains were observed to survive on lettuce plants up to 28 days after inoculation. Direct quantification by culture methods showed a Log10 4 decrease in the concentration of E. coli 14 days after inoculation, and a Log10 3 decrease in the concentration of L. innocua 10 days after inoculation. E. coli was detected in water samples up to 7 days after inoculation and L. innocua was detected up to 28 days by direct enumeration. Both strains were recovered from enriched samples up to 28 days after inoculation. These results demonstrate that E. coli and L. innocua strains are able to persist on lettuce after a single contamination event up until the plants reach a harvestable state. Furthermore, the persistence of E. coli and L. innocua in water for up to 28 days after inoculation illustrates the potential for multiple plant contamination events from stored irrigation water, emphasising the importance of ensuring that irrigation water is of a high quality.

Estimating Infiltration Properties Of Soil Using Infilt Model For Smart Irrigation

The infiltration characteristic of the soil is a major determinant of the efficiency and uniformity of surface irrigation application. Infiltration affects the advance, recession, runoff, and volume of infiltration during irrigation. This study has been carried out to estimate infiltration characteristics using irrigation advance data for furrow irrigation. Irrigation advance data for one field was collected at Latif farm, Sindh Agriculture University, Tandojam for three irrigation events and data sets for two fields of cotton in Queensland, Australia have also been used. To achieve the objectives of the study four different methods were employed viz: two-point method, computer model INFILT, Valiant one point and upadhyaya method. Employing these methods, infiltration parameters for three fields were determined and equations for cumulative infiltration and advance trajectories were evolved. Evaluation of the methods was undertaken to know the best method for the prediction of cumulative infiltration and advance. From the results, it has been concluded that the computer model INFILT V is the most accurate, reliable, and user-friendly method, as it performed well in all cases and can be used for achieving benefits in irrigation industry

Ambient Temperature Modulates Dissipation and Redistribution of Chlorpyrifos and 3,5,6-Trichloro-2-Pyridinol in Paddy Field

ABSTRACT Chlorpyrifos is an extensively used insecticide in the agriculture worldwide and was often detected in both surface waters and groundwater, posing threats to local residents’ health. Temporal changes and environmental fate of chlorpyrifos and 3,5,6-trichloro-2-pyridinol (TCP; the main degradation product of chlorpyrifos) were studied in field paddy lysimeters. On the other hand, batch sorption tests of both chlorpyrifos and TCP and dissipation test of chlorpyrifos under submerged condition were conducted for the paddy soil in the laboratory. Following field application, concentration of chlorpyrifos in the floodwater decreased rapidly by >90% of the initial concentration in the first two days. Higher temperature during the daytime, as compared to the nighttime, could not only lead to larger dissipation rates of chlorpyrifos and TCP in the floodwater in the first two days, but also cause greater release of TCP into the soil pore water for more days. A rain event at an early time (i.e., day 2) caused a transient peak release of chlorpyrifos and TCP into the soil pore water; however, no such changes occurred upon later rain or irrigation event(s). In future studies, due attention should be paid to the risk of the runoff and leaching of the weakly sorbing TCP.

Impact of Drought and Changing Water Sources on Water Use and Soil Salinity of Almond and Pistachio Orchards: 1. Observations

Soil salinity increases when growers are forced to use higher salinity irrigation waters due to water shortages. It is necessary to estimate the impact of irrigation water on soil properties and conditions for crop growth to manage the effects of salinity on perennial crops. Therefore, in this study, we monitored root zone salinity in five almond and pistachio orchards in eastern and western San Joaquin Valley (SJV), California (CA). Volumetric soil water contents and bulk electrical conductivities were measured at four root-zone depths. Evapotranspiration was measured by eddy covariance along with three other types of data. The first is seasonal precipitation and irrigation patterns, including the temporal distribution of rains, irrigation events, and irrigation water salinity. The second is soil chemistry, including the initial sodium adsorption ratio (SAR) and soil solute electrical conductivity (ECe). The third type is the physical properties, including soil type, hydraulic conductivity, and bulk density. As expected, we found low salinity at the eastern sites and higher salinity at the western sites. The western sites have finer textured soils and lower quality irrigation water; measured actual ET was about 90% of modeled crop ET. Across the three western sites, the annual average apparent leaching fraction ranged from 11 to 28%. At the eastern sites, measured ET almost exactly matched modeled crop ET each year. Apparent leaching fractions in the eastern sites were approximately 20%.

Effects of irrigation strategies and soil properties on the characteristics of deep percolation and crop water requirements for a variable rate irrigation system

Reducing deep percolation (DP) across the field is one of the main objectives of a variable rate irrigation (VRI) system under a semi-humid climate. A study was conducted in the North China Plain during the 2016 and 2017 maize growing seasons in a 1.64-ha one-quadrant plot irrigated by a VRI centre pivot irrigation system. The study was designed to quantify and compare the DP dynamics of three irrigation strategies, including soil water balance (SWB), measured soil water content (SWC), and a combination of SWB and rain forecasting for the next three days (RF). The area irrigated by the VRI system was delineated into three management zones (zones 1, 2, and 3) based on the available soil water holding capacity (AWC). Based on the seasonal cumulative DP, the zone-specific crop coefficient (Kc) for each zone was quantified to enhance the accuracy of the SWB method. The results indicated that high daily DP rates occurred during the initial and end growing seasons as well as following rainfall and irrigation events during the mid-season. The delay of DP after an intermittent large rainfall was observed in both seasons. The cumulative DP in zone 2 with a medium AWC and a uniform soil profile was 36% less than the mean values of DP for zones 1 and 3. Compared to the SWC and SWB methods, the cumulative DP for the RF treatment was reduced by 10% and 36%, respectively. During both seasons, the maximum DP values were observed in zones 2 and 3 under the SWB methods. The SWC method tended to increase the risk of DP for a coarse profile, whereas a lower sandy content soil tended to increase the risk for the SWB method. The mean Kc values derived based on DP for the initial, mid-season, and end of the late season stages were 0.86, 0.73, and 0.91 for zones 1, 2, and 3, respectively, with a 7% reduction compared to the Kc without considering DP. The seasonal crop water requirement determined by zone-specific Kc was reduced by 31 mm compared with the uniform Kc in different management zones. Our results suggested that the RF method exhibited promise for reducing DP, and the zone-specific Kc values were helpful to enhance the water savings of the SWB method for a VRI system.

The Effect of Deficit Irrigation Strategies on the Efficiency From Plant to Essential Oil Production in Peppermint (Mentha piperita L.)

The effect of deficit irrigation on water productivity in the water supply and utilization chain has been computed, employing a systematic and quantitative approach. By applying such an investigation, weaknesses and strengths of deficit irrigation strategies could be revealed, and actions and measures could be implemented to improve water productivity as much as possible. The peppermint plants were subjected to regulated deficit irrigation (RDI) and partial root-zone drying (PRD). Peppermint was cultivated under full irrigation (FI, control) and RDI treatments including RDI85, RDI70, RDI55, and RDI40, receiving 85, 70, 55, and 40% of FI treatment, respectively; PRD techniques including PRD70, PRD55, and PRD40, receiving 70, 55, and 40% of FI treatment in one side of the root-zone at each irrigation event, respectively during two cutting seasons. There was no significant improvement in leaves weight and dried yield step by applying deficit irrigation treatments. Leaves and aerial parts from the whole plant and dried yield as the main source of essential oil had the weakest function, which should be optimized to adjust and gain more efficiency. In the essential oil yield step, as a final procedure, the highest improvements were observed in PRD55 treatment with 90% improvement in efficiency compared to control treatment. According to the results and calculating water productivity, PRD55 treatment improved water productivity by 179% compared to the control treatment. Two-way ANOVA analysis, between deficit volume and the deficit applying method, showed that total water productivity was affected (increased) significantly by the deficit applying method. This implies the contribution of the PRD technique to enhance more signals than RDI-based signals, which resulted in more improvements in secondary metabolism production in peppermint.

Soil compaction in a new light: Know the cost of doing nothing – A cotton case study

Increased size of farm machinery has improved farm efficiency but at the risk of soil compaction. Here we present a novel approach investigating the effect of compaction due to in-field traffic by continuously monitoring crop canopy temperature and soil profile moisture and measuring crop yield in individual crop rows to determine the economic impact on cotton farming systems. Traffic by a tractor weighing 19.2 Mg either side of the plant row reduced lint yield by 27 % due to lower crop height, leaf area, biomass and fruit number. Elevated canopy temperature (Tc) in the compacted plots resulted in 30 % higher stress time (i.e. cumulative time when Tc is higher than the optimum Tc for cotton growth) compared with the non-compacted plots. Higher stress time in compacted plots was correlated with a 72 % and 27 % reduction in crop water use (estimated from change in soil water) at 0.3−0.5 m and 0.5 – 0.7 m depths, respectively. Water recharge in the soil profile from irrigation and rainfall was reduced by 16 % due to compaction with the highest reduction being 86 % at 0.3 – 0.5 m depth. These results demonstrate that compaction likely reduced root access to water below 0.3 m inducing water stress resulting in yield reduction. Tractors used for farm operations only compact one side of the bed, however, both sides are compacted in the absence of permanent wheel tracks. By comparison a dual tyre round module cotton picker weighing ∼32 Mg compacts 67 % of the rows on both sides and 33 % on one side suggesting greater economic loss in the following season compared to that estimated from the current study. Reductions in soil water recharge following irrigation and rainfall events due to compaction will further decrease farm efficiency and profitability. To our knowledge this is the first study related to soil compaction in any crop to show the direct relationship between yield, plant stress time and soil water dynamics at specific depths in profile. It is suggested that short term agronomic decisions (eg irrigation scheduling) need to be considered differently where compaction has been identified as limiting productivity. We recommend case studies be conducted to monitor the effect of compaction on commercial farm productivity and to demonstrate the cost of compaction across agricultural industries to drive practice change. Demonstrating the potential economic consequences of soil compaction by the integrated approach used in this study may encourage practice change to minimize compaction on farms.

Tomato and Watermelon Production with Mulches and Automatic Drip Irrigation in North Dakota

In North Dakota, agriculture contributes a large sector of the state’s economy, but vegetable production is limited due to the state’s climate condition. Inadequate soil moisture and low soil temperature are the two major factors prohibiting quality produce and high-yield vegetable production. In this study, a soil-water potential, sensor-based drip irrigation system was developed, designed, and installed to evaluate its application on tomato and watermelon productions in a two-year field experiment in 2019 and 2020. The experimental treatments were drip irrigation and no irrigation under three mulches: black plastic, clear plastic, and landscape fabric mulches. Irrigation was scheduled at 8:00 am for watermelon and 9:00 a.m. for tomato, with the ability for each irrigation event to be bypassed based on the soil moisture conditions. Due to rainfall differences in the two years, irrigation was barely needed in 2019, but in 2020, drip irrigation was applied frequently. On average, for the two-years’ field experiment, the highest yield for tomatoes was obtained from drip irrigation under black plastic drip irrigation treatment with 40.24 Mg ha−1 in 2020, whereas the highest yield for watermelon was from drip irrigation under clear plastic mulch with 165.55 Mg ha−1 in 2020. The effect of mulch, irrigation, and combined practices were analyzed based on the average fruit weight and diameter, electrical conductivity (EC), pH, and sugar content of the samples. The results showed that for watermelon, the average weight and diameter were significantly heavier and higher with irrigation treatments, but the EC and the pH values were significantly higher with mulch treatments. For tomatoes, the average weight, diameter, pH, and sugar content were all significantly higher with mulch treatment, but the EC was higher with irrigation treatment.

A Comparative Analysis of Root Growth Modules in HYDRUS for SWC of Rice under Deficit Drip Irrigation

Root distribution during rice cultivation is a governing factor that considerably affects soil water content (SWC) and root water uptake (RWU). In this study, the effects of activating root growth (using growth function) and assigning a constant average root depth (no growth during simulation) on SWC and RWU for rice cultivation under four deficit drip irrigation treatments (T90, T80, T70, and T60) were compared in the HYDRUS-2D/3D model version 3.03. A secondary objective was to investigate the effect of applied deficit irrigation treatments on grain yield, irrigation water use efficiency (IWUE), and growth traits of rice. The simulated DI system was designed to reflect a representative field experiment implemented in El-Fayoum Governorate, Egypt, during two successive seasons during 2017 and 2018. The deficit treatments (T90, T80, T70, and T60) used in the current study represent scenarios at which the first irrigation event was applied when the pre-irrigation average SWC within the upper 60 cm of soil depth was equal to 90%, 80%, 70%, and 60% of plant-available water, respectively. Simulation results showed that as water deficiency increased, SWC in the simulation domain decreased, and thereby, RWU decreased. The average SWC within the root zone during rice-growing season under different deficit treatments was slightly higher when activating root growth function than when considering constant average root depth. Cumulative RWU fluxes for the case of no growth were slightly higher than for the case of root growth function for T90, T80, and T70 accounting for 1289.50, 1179.30, and 1073.10 cm2, respectively. Average SWC during the growth season (24 h after the first irrigation event, mid-season, and 24 h after the last irrigation event) between the two cases of root growth was strongly correlated for T90, T80, T70, and T60, where r2 equaled 0.918, 0.902, 0.892, and 0.876, respectively. ANOVA test showed that there was no significant difference for SWC between treatments for the case of assigning root growth function while the difference in SWC among treatments was significant for the case of the constant average root depth, where p-values equaled 0.0893 and 0.0433, respectively. Experimental results showed that as water deficiency decreased, IWUE increased. IWUE equaled 1.65, 1.58, 1.31, and 1.21 kg m−3 for T90, T80, T70, and T60, respectively. Moreover, higher grain yield and growth traits of rice (plant height, tillers number plant−1, panicles length, panicle weight, and grain number panicles−1) were obtained corresponding to T90 as compared with other treatments. Activating the root growth module in HYDRUS simulations can lead to more precise simulation results for specific dates within different growth stages. Therefore, the root growth module is a powerful tool for accurately investigating the change in SWC during simulation. Users of older versions of HYDRUS-2D/3D (version 2.05 and earlier) should consider the limitations of these versions for irrigation scheduling.