Mm For Maize Research Articles

Temperature increase may not necessarily penalize future yields of three major crops in Xinjiang, Northwest China

Future food production is at risk due to climate change, particularly in arid regions with limited water resources and extensive irrigated agriculture. This study utilized the DSSAT model in conjunction with downscaled data from 21 global climate models (GCMs) under two shared socioeconomic pathways (SSP2–4.5 and SSP5–8.5) to assess the impact of projected climate change on irrigated crop phenology, yield, and evapotranspiration (ETc) of cotton, maize, and winter wheat in the Shihezi region of Xinjiang, China. The results indicated that temperature and precipitation in the region were expected to increase gradually from 2021 to 2100. Climate change has resulted in earlier anthesis and physiological maturity of all three crops. Future climatic conditions could reduce maize yields to 16.02 %. Conversely, the yields of cotton and winter wheat increased, with cotton yields rising by 1.23–10.94 % and winter wheat yields by 3.19–14.07 %. Additionally, ETc for cotton, maize, and winter wheat could rise in the future. The irrigation water demands could increase by 41.1–96.4 mm for cotton and 27.3–37.9 mm for maize, while the demand for winter wheat could decrease by 0.5–36.2 mm. Warming was significantly correlated with the changes in the yield and water use efficiency (WUE) of cotton, maize, and winter wheat. The temperature increases of +0.5°C to +3.0°C (relative to baseline) at 0.5°C intervals were analyzed to evaluate their effects on yield and WUE. The yields varied from −0.93 % to 6.15 % for cotton, −43.42 % to −7.99 % for maize, and 4.28–9.92 % for winter wheat. The WUE changes ranged from −29.03 % to −1.08 % for cotton, −43.06 % to −7.66 % for maize, and 0.69–3.47 % for winter wheat. Contrary to the common belief that rising temperatures generally harm crop yields, our study suggests that temperature fluctuations may benefit certain crops in specific regions. These results could provide theoretical guidance for implementing adaptive measures to future climate change in regions with conditions similar to Shihezi, Xinjiang, China, to ensure crop security and sustainable water management.

Applications of land surface model to economic and environmental-friendly optimization of nitrogen fertilization and irrigation

Land surface models (LSMs) have prominent advantages for exploring the best agricultural practices in terms of both economic and environmental benefits with regard to different climate scenarios. However, their applications to optimizing fertilization and irrigation have not been well discussed because of their relatively underdeveloped crop modules. We used a CLM5-Crop LSM to optimize fertilization and irrigation schedules that follow actual agricultural practices for the cultivation of maize and wheat, as well as to explore the most economic and environmental-friendly inputs of nitrogen fertilizer and irrigation (FI), in the North China Plain (NCP), which is a typical intensive farming area. The model used the indicators of crop yield, farm gross margin (FGM), nitrogen use efficiency (NUE), water use efficiency (WUE), and soil nitrogen leaching. The results showed that the total optimal FI inputs of FGM were the highest (230 ± 75.8 kg N ha−1 and 20 ± 44.7 mm for maize; 137.5 ± 25 kg N ha−1 and 362.5 ± 47.9 mm for wheat), followed by the FIs of yield, NUE, WUE, and soil nitrogen leaching. After multi-objective optimization, the optimal FIs were 230 ± 75.8 kg N ha−1 and 20 ± 44.7 mm for maize, and 137.5 ± 25 kg N ha−1 and 387.5 ± 85.4 mm for wheat. By comparing our model-based diagnostic results with the actual inputs of FIs in the NCP, we found excessive usage of nitrogen fertilizer and irrigation during the current cultivation period of maize and wheat. The scientific collocation of fertilizer and water resources should be seriously considered for economic and environmental benefits. Overall, the optimized inputs of the FIs were in reasonable ranges, as postulated by previous studies. This result hints at the potential applications of LSMs for guiding sustainable agricultural development.

Unveiling the Thirst: Revealing the Water Requirements of Gujrat's Thriving Crops using CROPWAT 8.0

Water plays an essential role in agriculture, serving as a primary reserve that directly impacts crop production and food security. Water conservation is critical for sustainable agriculture and the well-being of communities and ecosystems, chiefly due to the increasing global demand and rising water dearth concerns. The water needs of crops and irrigation scheduling in the district Gujrat, Pakistan, are currently missing enough information. Therefore, this study was conducted to determine the crop water requirements and establish irrigation schedules for the major crops in district Gujrat, Pakistan. The crop water requirement (CWR) and irrigation schedules were determined by CROPWAT 8.0 by using the input climate data obtained from the POWER-NASA website from 1991-2020. Other than climatic data, crops (wheat, rice, sugarcane, and maize) and soil information were added from CROPWAT 8.0 pre-existing data. The crop planting dates were estimated by Ayub Agriculture Research Institute (AARI). The gross and net crop water requirements are 624.3 mm and 491.3 mm for wheat, 1805.2 mm and 1768.3 mm for rice, 4135.1 mm and 3537.2 mm for sugarcane, and 1203.5 mm and 1051.4 mm for maize. The deployment of CROPWAT 8.0 proves to be valuable in precisely assessing crop water requirements and computing irrigation scheduling. The study's outcomes show the potential to boost food production and aid in well-organized water reserve management.

Seasonal variation and controlling factors of evapotranspiration over dry semi-humid cropland in Guanzhong Plain, China

The Guanzhong Plain is a critical food production area in the Yellow River Basin that frequently suffers from water shortages. In this study, long-term (June 2013 to June 2018) water and energy fluxes were observed, and path analysis was conducted over an irrigated winter wheat (Triticum aestivum L.) / summer maize (Zea mays L.) rotation field to identify the controlling factors of evapotranspiration (ET). Total ET for each crop year ranged from 627 to 775 mm, with an average growing season ET of 398 mm for wheat and 310 mm for maize. There is significant seasonal variation in both ET and surface conductance (Gs). Daily ET varied from 0.0 to 6.0 mm d–1 for wheat and 0.0 to 6.7 mm d–1 for maize. The peak daily values of Gs were 29.5 mm s–1 for wheat and 19.5 mm s–1 for maize. The direct and indirect effects of environmental and biological factors—net radiation (Rn), surface conductance (Gs), saturation vapor pressure deficit (VPD), leaf area index (LAI), air temperature (Tair), and volumetric soil water content (VWC)—on ET were calculated using the path analysis method. Rn was determined to be the primary controlling factor of ET for both the summer maize and winter wheat growing seasons. Also, Gs was found to be another controlling factor that has more controlling power in the summer maize growing season than in the winter wheat season. VPD had a significant positive and direct effect on ET for both of the crop seasons, while it had a significant negative and indirect effect on ET through Gs in the summer maize season. VWC and Tair only directly affected the wheat ET. In addition, VWC had two significant paths that can indirectly affect ET through LAI and Gs. The revealed seasonal patterns and controlling factors of evapotranspiration in this agroecosystem provide a theoretical basis for optimizing water resources management of the Yellow River.

An Attempt to Evaluate the Performance Parameters of a Precision Vacuum Seeder in Different Seed Drop Height

This study examined the effects of seed drop height changing depending on furrow openers of precision seeders, and the forward speed of tractors which is constantly aimed to be increased by producers on the uniformity of seed distribution. The experiments were made with a precision seeder unit positioned on a sticky belt trial setup at seed drop heights of 100, 200 and 300 mm, the forward speeds of 0.5, 1.0, and 1.5 m s-1, and the vacuum pressures of 6.0, 7.5, and 9.0 kPa. Maize and sunflower seeds were used in experiments. According to the results, the effects of seed drop height and forward speed on seed spacing and deviation from row were significant for both seed types (P<0.01). The increase in the forward speed led to a deviation of approximately 15 mm in maize and 17 mm in sunflower between the mean seed spacing and the target seed spacing. In general, miss and multiple indices were found to be fewer than 9%. The optimum performance of the seeder unit in sowing sunflower and maize was obtained at the seed drop height of 100 mm, the forward speed of 0.5 m s-1, and the vacuum pressure of 9.0 kPa. Consequently, it is suggested that, in contrast to what is demanded, the forward speed cannot be increased as much as one desires, and the dimensions of furrow openers that changed depending on the seed drop height should be designed under certain standards.

Inter-relationships between water depletion and temperature differential in row crop canopies in a sub-humid climate

Irrigation has a great impact on global food security as it contributes to the majority of the world’s agricultural food supply. It is essential to judiciously utilize water resources through efficient irrigation management since the majority of U.S. groundwater aquifers are rapidly depleting. Thus, quantification of the relationships between water depletion and environmental factors is important for understanding crop response to varying levels of water stresses that depletion can cause. The objectives of this research were to: 1) investigate the relationship between root zone water depletion (Drw) and canopy temperature differential (ΔT) at different ranges of Drw; and 2) develop upper (water stressed) and lower (non-water stressed) baselines for quantification of crop water stress index (CWSI) in a sub-humid climate. The research was conducted over maize and soybean during 2018, 2019, and 2020 growing seasons. Sensor node stations comprising of an infrared thermometer and three soil water sensors were installed at various sites over maize and soybean fields. ΔT tends to increase with the increase in Drw when the range of Drw includes values greater than 170 mm for maize and values greater than 160 mm for soybean. The results indicate that ΔT and Drw are unrelated until a soil-water depletion threshold is attained, and these Drw threshold values could be considered as indicators to trigger irrigation for efficient agricultural water management. To the best of the authors’ knowledge, the research is the first to develop upper and lower CWSI baselines for east-central Nebraska. The baselines developed in this study could facilitate the quantification of CWSI for irrigation scheduling of maize and soybean in east-Central Nebraska. Future work should aim to investigate the potential in using Drw and/or ΔT to determine efficient water allocation and if a threshold CWSI could be used for timing of irrigation to prevent yield loss.

Evaluation of maize-based intercropping on runoff, soil loss, and yield in foothills of the Indian sub-Himalayas

SummarySoil and nutrients losses due to soil erosion are detrimental to crop production, especially in the hilly terrains. An experiment was carried out in three consecutive cropping seasons (2012–2015) with four treatments: sole maize; sole maize with plastic mulch; maize and cowpea under plastic mulching; and maize and soybean under plastic mulching in randomized block design (RBD) to assess their impact on productivity, profitability, and resource (rainwater, soil, and NPK nutrients) conservation in the Indian sub-Himalayan region. The plot size was 9 × 8.1 m with 2% slope, and runoff and soil loss were measured using a multi-slot devisor. The results showed that mean runoff decreased from 356 mm in sole maize with plastic mulch plots to 229 mm in maize + cowpea intercropping with plastic mulch, representing a reduction of 36% and corresponding soil loss reduction was 41% (from 9.4 to 5.5 t ha−1). The eroded soil exported a considerable amount of nitrogen (N) (13.2–31.4 kg ha−1), phosphorous (P) (0.5–1.7 kg ha−1), and potassium (K) (9.9–15.6 kg ha−1) and was consistently lower in maize + cowpea intercropping. The maize equivalent yield (MEY) was significantly higher in maize + cowpea with plastic mulch intercropping than the other treatments. These results justify the need to adopt maize with alternate legume intercrops and plastic mulch. This strategy must be done in a way guaranteeing high yield stability to the smallholder farmers of the Indian sub-Himalayan region.

Effects of irrigation and nitrogen fertilization management on crop yields and long-term dynamic characteristics of water and nitrogen transport at deep soil depths

Appropriate irrigation and nitrogen (N) management practices should be implemented to obtain high grain yields while considering the influence of water and N leaching on groundwater in the intensively cropped winter wheat (Triticum aestivum)-maize (Zea mays L.) rotation system. The calibrated RZWQM2 model was used to explore long-term (1984–2017) effects of irrigation and N fertilization on crop yield, water and nitrogen use efficiency, deep percolation water (DPW), N leaching loss (NLL), and their effects on deep soil layers (2−30 m) in this rotation system in the Jinghui Canal irrigation area of the Guanzhong Plain in China. Results showed that crop yields increased with increasing N rate. The critical N application rates of 140 and 240 kg N ha−1 coupled with 75 and 90 mm of irrigation for maize and wheat, respectively, resulted in high yields (7535 and 8977 kg ha−1), water use efficiency (2.22, 2.07 kg m-3), and nitrogen use efficiency (44.56, 40.78 kg kg−1). The simulated DPW values were 69 and 110 mm for maize and wheat, respectively, and NLL values were 25.36 and 25.47 kg ha−1. Crop yield and NLL for wheat were more sensitive to N application timing than maize yield and NLL, indicating that split N applications of two application times and three application times for maize and wheat, respectively, could be a more effective way of applying N fertilizer. DPW fluxes increased from 0.021-0.024 (varied over the 2−30 m depth) to 0.107-0.110 mm d−1 for irrigation ranging from 60 to 135 mm. The response times for DPW to be observed at the groundwater depth of 30 m could range from one year to more than two years, with DPW velocities of 0.034 and 0.077 m d−1 for 60 and 135 mm irrigation application amounts, respectively. NLL flux increased with added irrigation and N application rate, while decreasing exponentially with soil depth. Annual recharge of NO3-N to the groundwater (0.15–6.2 kg N ha−1) with lower irrigation amounts (60−90 mm) could be neglected, but higher irrigations (≥105 mm) even with lower N application rates could cause groundwater contamination. Therefore, comprehensively considering the effects of irrigation and fertilization practices on grain yields and groundwater could improve the sustainability of the agro-hydrological environment and agricultural production.

Net ecosystem exchange of CO2 and H2O fluxes from irrigated grain sorghum and maize in the Texas High Plains

Net ecosystem exchange (NEE) of carbon dioxide (CO2) and water vapor (H2O) fluxes from irrigated grain sorghum (Sorghum bicolor L. Moench) and maize (Zea mays L.) fields in the Texas High Plains were quantified using the eddy covariance (EC) technique during 2014–2016 growing seasons and examined in terms of relevant controlling climatic variables. Eddy covariance measured evapotranspiration (ETEC) was also compared against lysimeter measured ET (ETLys). Daily peak (7-day averages) NEE reached approximately −12 g C m−2 for sorghum and −14.78 g C m−2 for maize. Daily peak (7-day averages) ETEC reached approximately 6.5 mm for sorghum and 7.3 mm for maize. Higher leaf area index (5.7 vs 4–4.5 m2 m−2) and grain yield (14 vs 8–9 t ha−1) of maize compared to sorghum caused larger magnitudes of NEE and ETEC in maize. Comparisons of ETEC and ETLys showed a strong agreement (R2 = 0.93–0.96), while the EC system underestimated ET by 15–24% as compared to lysimeter without any corrections or energy balance adjustments. Both NEE and ETEC were not inhibited by climatic variables during peak photosynthetic period even though diurnal peak values (~2-weeks average) of photosynthetic photon flux density (PPFD), air temperature (Ta), and vapor pressure deficit (VPD) had reached over 2000 μmol m−2 s−1, 30 °C, and 2.5 kPa, respectively, indicating well adaptation of both C4 crops in the Texas High Plains under irrigation. However, more sensitivity of NEE and H2O fluxes beyond threshold Ta and VPD for maize than for sorghum indicated higher adaptability of sorghum for the region. These findings provide baseline information on CO2 fluxes and ET for a minimally studied grain sorghum and offer a robust geographic comparison for maize outside the United States Corn Belt. However, longer-term measurements are required for assessing carbon and water dynamics of these globally important agro-ecosystems.

Estimating the actual evapotranspiration and deep percolation in irrigated soils of a tropical floodplain, northwest Ethiopia

The deep percolation and actual evapotranspiration from flood irrigation in tropical floodplains were predicted using a numerical model, Hydrus-1D, and a bucket type water balance model. Field experiments were conducted on onion and maize crops grown from December 2015 to May 2016 in small irrigation schemes found in the Lake Tana floodplains of Ethiopia. Experimental fields were selected along a topographic transect to account for soil and groundwater variability. Irrigation volumes were measured using V-notches and irrigation depths (400–550 mm) were calculated, and daily groundwater levels were monitored manually from piezometers installed in the fields. The soil profiles were described at each field and physical properties (texture, FC, PWP, BD, and OM) were measured at each horizon which were used to derive model input parameters. Soil hydraulic properties (residual and saturated moisture content, saturated hydraulic conductivity, parameters related to: pore size distribution n, air entry α and pore connectivity l) were derived using KNN pedotransfer functions for tropical soils and fitted using Retention Curve Program for Unsaturated Soils, RETC. The seasonal actual evapotranspiration estimated by Hydrus and water balance models ranged from 320 to 360 mm for onion and from 400 to 470 mm for maize. The seasonal deep percolation estimated from both models was 12–41% of applied irrigation and with this flood irrigation management; the deep percolation is very high. Implementing precise irrigation and water saving practices that minimize deep percolation and unproductive excessive consumptive use are required to achieve the growing food demand with the available water. When less detailed information is available, the water balance model can be an alternative to predict deep percolation and actual evapotranspiration.

Effect of Water Sources on the Radicle Elongation of some Cash Crops from Nigeria

Five water sources were used to germinate four different cash crops from Nigeria. The water was sourced from salty water, river water, stream water, rain water and borehole water. The effect of these water sources on the radicle elongation were measured on the seeds of maize ( Zea mays L.) variety TZL Comp 4C3DTP2, cowpea ( Vigna unguiculata (L) Walp ssp. unguiculata ) variety ITO7K-299-6, groundnut ( Arachis hypogaea L.) and melon ( Citrullus colocynthis (Linn.) Schrad) respectively. The physicochemical properties of the different water used varied from one location to another. The pH of salty water, river water, rain water and borehole water were alkaline except stream water. The Ca, Mg and total hardness were high in borehole water than other water sources. Salty water had high Ca, Mg, K, Mn, Fe, Zn, Cu, Cl, SO 4 contents when compared with others. The highest radicle growth length after five days were obtained with stream water at 25.36 ± 7.461 mm, 4.47 ± 1.438 mm, 4.75 ± 1.975 mm, 6.24 ± 1.018 mm for maize, melon, cowpea and groundnut respectively. There was significant difference (p>0.05) amongst treatments. The seeds of monocotyledon (maize) gave higher radicle length in different water sources when compared to dicotyledonous seeds (melon, cowpea, and groundnut). The study revealed a reduction in radicle growth length with seeds germinated with salty water.

EFFECT OF SOIL TILLAGE AND PLANT RESIDUE ON SURFACE ROUGHNESS OF AN OXISOL UNDER SIMULATED RAIN

Surface roughness of the soil is formed by mechanical tillage and is also influenced by the kind and amount of plant residue, among other factors. Its persistence over time mainly depends on the fundamental characteristics of rain and soil type. However, few studies have been developed to evaluate these factors in Latossolos (Oxisols). In this study, we evaluated the effect of soil tillage and of amounts of plant residue on surface roughness of an Oxisol under simulated rain. Treatments consisted of the combination of the tillage systems of no-tillage (NT), conventional tillage (CT), and minimum tillage (MT) with rates of plant residue of 0, 1, and 2 Mg ha-1 of oats (Avena strigosa Schreb) and 0, 3, and 6 Mg ha-1 of maize (Zea mays L.). Seven simulated rains were applied on each experimental plot, with intensity of 60±2 mm h-1 and duration of 1 h at weekly intervals. The values of the random roughness index ranged from 2.94 to 17.71 mm in oats, and from 5.91 to 20.37 mm in maize, showing that CT and MT are effective in increasing soil surface roughness. It was seen that soil tillage operations carried out with the chisel plow and the leveling disk harrow are more effective in increasing soil roughness than those carried out with the heavy disk harrow and leveling disk harrow. The roughness index of the soil surface decreases exponentially with the increase in the rainfall volume applied under conditions of no tillage without soil cover, conventional tillage, and minimum tillage. The oat and maize crop residue present on the soil surface is effective in maintaining the roughness of the soil surface under no-tillage.

Development and Evaluation of Self-propelled Multicrop Planter for Hill Agriculture

A two-row self-propelled multicrop planter for hilly areas was developed, and its performance evaluated for planting of maize and soybean seeds. Power was transmitted from a 1.57 kW engine to the drive wheels and metering mechanism through chain and sprockets. Inclined plate type seed metering mechanism was used in the planter. Seeds were placed in the furrows at desired depths through adjustable system. The average depths of seed placement were 22.50 mm and 21.50 mm for maize and soybean, respectively. The average draft requirement for the planter was 1.57 kN, which was within the capacity of the power source. Average field capacity of 0.11 ha.h-1 was obtained for continuous operation of the planter at an average forward speed of 1.36 km.h-1 for planting both maize and soybean. The average field efficiency and field machine index of the planter were observed to be 80.98 and 71.78 %, respectively. The man-hour requirement for planting of one hectare land with the planter was 9.09. The cost of sowing with the planter was Rs.1100/- per hectare, which saved 64.80 % operational costs as compared to manual planting. The savings in man-hours and cost of planting were substantial.

Actual evapotranspiration and dual crop coefficients for dry-seeded rice and hybrid maize grown with overhead sprinkler irrigation

In lieu of the decreasing availability of water for irrigated rice, we examined two alternatives to traditional rice cultivation on puddled and saturated soil–maize and dry-seeded rice production grown with an overhead sprinkler irrigation system. We characterized the inter-seasonal daily variations of actual crop evapotranspiration (ET), transpiration (T), and evaporation (E) using the eddy covariance (EC) technique during 2011 and 2012 dry seasons. The average growing season ET rate of maize was 3.90mmd−1 in 2011 and 3.74mmd−1 in 2012. For the dry-seeded rice, the average growing season ET rate was 4.36mmd−1 in 2011 and 4.13mmd−1 in 2012. Growing season ET of maize (484mm) and dry-seeded rice (523mm) in 2011 were higher than during 2012 (453mm for maize and 475mm for dry-seeded rice) because of higher net radiation (Rn) in 2011. Partitioning ET showed that T accounted for 66–74% of seasonal ET for maize and 53–60% for dry-seeded rice. On average, dry-seeded rice had 6.5% more ET than maize due to higher irrigation water inputs. The average total water input (irrigation+precipitation) for maize was 618mm while that of the dry-seeded rice was 908mm. The large difference between crop coefficient (Kc) and basal crop coefficient (Kcb) values during the initial and crop development stages of both maize and dry-seeded rice provides a good opportunity to optimize irrigation water input by designing a more efficient irrigation schedule that is appropriate to the water needs of the crops.

Mapping Spatially Interpolated Precipitation, Reference Evapotranspiration, Actual Crop Evapotranspiration, and Net Irrigation Requirements in Nebraska: Part II. Actual Crop Evapotranspiration and Net Irrigation Requirements

With the world population expected to increase by 3.7 billion people by 2050, it is anticipated that the additional food and fiber required to feed future generations will impose greater pressure on freshwater resources. Approximately 70% to 80% of global freshwater withdrawal is for irrigation, and more than 40% of food is produced on irrigated land, which comprises only 18% of the total land allocated to food and fiber production. To evaluate future water supply and demand in relation to food production, it is necessary to quantify actual crop evapotranspiration (ETa) and irrigation water requirements (NIR) of various crop production systems. Long-term (1986-2009) growing season (1 May to 30 September) ETa and NIR for maize and soybean were quantified for all 93 counties in Nebraska. There was a gradual decrease in ETa totals from the western part (zone 1) of the state toward the eastern part (zone 4). For maize, the growing season total ETa ranged from 801 mm in Cheyenne County (zone 1) to 484 mm in Butler County (zone 4), with a statewide average of 634 mm. For soybean, the growing season ETa ranged from 705 mm in Cheyenne County to 430 mm in Butler County, with a statewide average of 559 mm. On a statewide average, maize ETa was 75 mm (12%) higher than soybean ETa. There was a gradual decrease in NIR totals from the western part of the state toward the eastern part. The NIR for maize ranged from 575 mm in the western part to 150 mm in eastern Nebraska, with a statewide average of 289 mm. Soybean NIR ranged from 467 mm in the western part to 111 mm in the eastern counties, with a statewide average of 227 mm. On average, the NIR was greater in zone 1 than in zone 4 by 319 mm (61.7%) for maize and 267 mm (63.04%) for soybean. July was the most critical for both crops in terms of contribution of precipitation to ETa and NIR. The statewide average July NIR was observed as 133 mm and 127 mm for maize and soybean, respectively. The statewide long-term average minimum NIR for maize was observed in 1993 as 90 mm (±88 mm) and in 1996 as 60 mm (±100 mm) for soybean, and the maximum value was obtained in 2002 as 525 mm (±188 mm) for maize and 433 mm (±173 mm) for soybean. In the last 24-year period, the statewide average maize NIR increased by 21 mm, and the average soybean NIR increased by 18 mm. The long-term average statewide NIR was 268 mm (±154 mm) for maize and 196 mm (±137 mm) for soybean. Mapping and quantification of ETa and NIR can help water users and managers, decision makers, and policymakers better allocate water resources and develop water resources management strategies for enhancing crop water productivity. These datasets and analyses can also aid in identifying locations where long-term trends in ETa, NIR, and crop productivity are decreasing so that more robust resource reallocation practices can be adopted to improve agricultural productivity.

Implementing the dual crop coefficient approach in interactive software: 2. Model testing

Abstract This paper is the second of a two-part series, with the first part describing the SIMDualKc model, an irrigation scheduling simulation tool that employs the dual crop coefficient approach for calculating daily crop ET and then performs a water balance for a cropped soil. The model was applied, calibrated and validated for rainfed and basin irrigated maize (Coruche, Portugal), rainfed and surface irrigated wheat (Aleppo, Syria), and furrow irrigated cotton (Fergana, Central Asia). Results show good agreement between available soil water content observed in the field and that predicted by the model. Results indicate that the calibrated model does not tend to over- or underestimate available soil water over the course of a season, and that the model, prior to calibration, and using standard values for many parameters, also performed relatively well. After calibration, the average growing season maximum estimation errors were 10 mm for maize, 8 mm for winter wheat and 9 mm for cotton, i.e., respectively 3.6, 2.9 and 5.0% of total available water. Results indicate that the separation between evaporation and transpiration and the water balance calculation procedures are accurate enough for use in operational water management. The indicators used for assessing model performance show the model to accurately simulate the water balance of several crops subjected to a variety of irrigation management practices and various climate conditions. In addition, the model was applied to alternative irrigation management scenarios and related results are discussed aiming at assessing the model's ability to support the development of alternative active water management strategies.

Changes in evapotranspiration over irrigated winter wheat and maize in North China Plain over three decades

Abstract Evapotranspiration (ET) is an important component of the water cycle at field, regional and global scales. This study used measured data from a 30-year irrigation experiment (1979–2009) in the North China Plain (NCP) on winter wheat (Triticum aestivum L.) and summer maize (Zea mays L.) to analyze the impacts of climatic factors and crop yield on ET. The results showed that grass reference evapotranspiration (ETo, calculated by FAO Penmen–Monteith method) was relatively constant from 1979 to 2009. However, the actual seasonal ET of winter wheat and maize under well-watered condition gradually increased from the 1980s to the 2000s. The mean seasonal ET was 401.4 mm, 417.3 mm and 458.6 mm for winter wheat, and 375.7 mm, 381.1 mm and 396.2 mm for maize in 1980s, 1990s and 2000s, respectively. The crop coefficient (Kc) was not constant and changed with the yield of the crops. The seasonal average Kc of winter wheat was 0.75 in the 1980s, 0.81 in the 1990s and 0.85 in the 2000s, and the corresponding average grain yield (GY) was 4790 kg ha−1, 5501 kg ha−1 and 6685 kg ha−1. The average Kc of maize was 0.88 in the 1980s, 0.88 in the 1990s and 0.94 in the 2000s, with a GY of 5054 kg ha−1, 7041 kg ha−1 and 7874 kg ha−1, respectively, for the three decades. The increase in ET was not in proportion to the increase in GY, resulting improved water use efficiency (WUE). The increase in ET was possibly related to the increase in leaf stomatal conductance with renewing in cultivars. The less increase in water use with more increase in grain production could be partly attributed to the significant increase in harvest index. The results showed that with new cultivars and improved management practices it was possible to further increase grain production without much increase in water use.

Nível crítico de toxidez do ácido acético em culturas alternativas para solos de várzea

A deficiente drenagem natural dos solos de várzea proporciona um ambiente anaeróbico, favorecendo a formação de substâncias tóxicas, como o ácido acético, que afeta o desempenho de espécies de sequeiro nesses ecossistemas. O presente estudo foi conduzido com os objetivos de avaliar os efeitos e estabelecer os níveis críticos de toxidez do ácido acético para culturas de sequeiro alternativas para solos de várzea, como o milho, a soja e o sorgo. Os tratamentos constaram de seis doses de ácido acético, entre zero e 8mM, para milho (Embrapa BRS 1001) e sorgo (BRS 307), e quatro doses entre zero e 4mM, para soja (Embrapa BRS 133), com seis repetições, em delineamento completamente casualizado. Os indicadores avaliados foram os parâmetros morfológicos do sistema radicular (comprimento, raio, área e massa seca relativas) e concentração de N, P, K, Ca e Mg e massa seca relativa da parte aérea das plantas. O ácido acético foi tóxico para as culturas do milho, da soja e do sorgo, causando reduções no comprimento, na área e na massa seca radicular e na massa seca e na concentração de N, P, K, Ca e Mg da parte aérea. As concentrações de ácido acético responsáveis pela inibição de 50% do comprimento radicular relativo foram de 2mM para a soja e 2,7mM para o milho e o sorgo.

Nebraska Agricultural Water Management Demonstration Network (NAWMDN): Integrating Research and Extension/Outreach

Abstract . Maximizing the net benefits of irrigated plant production through appropriately designed agricultural water management programs is of growing importance in Nebraska, and other western and Midwestern states, because many areas are involved in management and policy changes to conserve irrigation water. In Nebraska, farmers are being challenged to practice conservation methods and use water resources more efficiently while meeting plant water requirements and maintaining high yields. Another challenge Nebraska experiences in it's approximately 3.5-million-ha irrigated lands is limited adoption of newer technologies/tools to help farmers better manage irrigation, conserve water and energy, and increase plant water use efficiency. In 2005, the Nebraska Agricultural Water Management Demonstration Network (NAWMDN or Network) was formed from an interdisciplinary team of partners including the Natural Resources Districts (NRD); USDA-NRCS; farmers from south central, northeast, west central, and western Nebraska; crop consultants; and University of Nebraska-Lincoln faculty. The main goal of the Network is to enable the transfer of high quality research-based information to Nebraskans through a series of demonstration projects established in farmers' fields and implement newer tools and technologies to address and enhance plant water use efficiency, water conservation, and reduce energy consumption for irrigation. The demonstration projects are supported by the scientifically-based field research and evaluation projects conducted at the University of Nebraska-Lincoln, South Central Agricultural Laboratory located near Clay Center, Nebraska. The Network was formed with only 15 farmers as collaborators in only one of the 23 NRDs in 2005. As of late 2009, the number of active collaborators has increased to over 300 in 12 NRDs and 35 of 93 counties. The Network is impacting both water and energy conservation due to farmers adopting information and newer technologies for irrigation management. The NAWMDN is helping participants to improve irrigation management and efficiency by monitoring plant growth stages and development, soil moisture, and crop evapotranspiration. As a result, they are reducing irrigation water application amounts and associated energy savings is leading to greater profitability to participating farmers. For example, surveys of 300 NAWMDN participants in 2008 estimated water conservation at an average of 66 mm for maize and 55 mm for soybean on 114,000 ha (58,000 ha of maize and about 56,000 ha of soybean). With 2008 diesel fuel prices, this water conservation was an equivalent of $2,814,000 and $2,270,000 for maize and soybean, respectively, in energy costs saved for the land area represented. Since the beginning of the NAWMDN, over 8,650 producers, crop consultants, and agricultural industry personnel have been reached and educated at over 231 meetings. This article describes the goals and objectives of the Network, technical and educational components, operational functions, and procedures used in the NAWMDN. The quantitative impacts in terms of water and energy conservation are reported.

Determination of growth-stage-specific crop coefficients ( KC) of maize and sorghum

A ratio of crop evapotranspiration (ET C) to reference evapotranspiration (ET O) determines a crop coefficient ( K C) value, which is related to specific crop phenological development to improve transferability of the K C values. Development of K C can assist in predicting crop irrigation needs using meteorological data from weather stations. The objective of the research was conducted to determine growth-stage-specific K C and crop water use for maize ( Zea Mays) and sorghum ( Sorghum bicolor) at Texas AgriLife Research field in Uvalde, TX, USA from 2002 to 2008. Seven lysimeters, weighing about 14 Mg, consisted of undisturbed 1.5 m × 2.0 m × 2.2 m deep soil monoliths. Six lysimeters were located in the center of a 1-ha field beneath a linear-move sprinkler system equipped with low energy precision application (LEPA). A seventh lysimeter was established to measure reference grass ET O. Crop water requirements, K C determination, and comparison to existing FAO K C values were determined over a 3-year period for both maize and sorghum. Accumulated seasonal crop water use ranged between 441 and 641 mm for maize and between 491 and 533 mm for sorghum. The K C values determined during the growing seasons varied from 0.2 to 1.2 for maize and 0.2 to 1.0 for sorghum. Some of the values corresponded and some did not correspond to those from FAO-56 and from the Texas High Plains and elsewhere in other states. We assume that the development of regionally based and growth-stage-specific K C helps in irrigation management and provides precise water applications for this region.