Alternate Partial Root-zone Drip Irrigation Research Articles

Biochar effects on soil nitrogen retention, leaching and yield of perennial citron daylily under three irrigation regimes

Biochar can serve as a soil amendment to immobilize soil nitrogen (N) and reduce N leaching from cropland without negative effect on crop yield. However, the interaction effect of biochar application and irrigation regimes on soil N status (N retention and N loss) and crop yield is rarely reported in the open perennial vegetable field. A two-years field trial (transplanting in first year and consecutive growth in second year) was conducted in citron daylily vegetable cropping system on a sandy brown alluvial soil. Two biochar application rates (0 and 30 t ha−1) and three irrigation regimes (CDI, conventional drip irrigation; WSDI, water-saving drip irrigation with 80% of full irrigation quota; APRDI, alternate partial root-zone drip irrigation with 80% of full irrigation quota) were included. The response of crop yield and soil N status to both biochar application and irrigation regimes varied across planting years for perennial citron daylily. After the first planting year's harvest, APRDI enhanced flower bud yield by 18–28% compared to CDI and WSDI, likely due to improved nitrate use efficiency evidenced by lower soil nitrate retention in the surface soil (0–20 cm) post-harvest. However, biochar application resulted in a reduction of yield by 27% under APRDI. Additionally, WSDI with reduced yields, decreased soil TN in the sub-surface layer (20–50 cm) with 9–19% by comparison with other two irrigation regimes, resulting in higher TN concentration in the soil solution (14–28%) in and thus an increased risk for N leaching. However, after the second harvest year, there were no variations in crop yield induced by biochar application and irrigation regimes. Irrigation regimes exhibited limited influence on soil N status, while biochar application mitigated soil nitrogen decline in the 0–50 cm layer by enhancing organic nitrogen retention capacity for nearly 16–85%. Furthermore, the lowest TN concentration in the soil solution in the sub-surface layer (20–50 cm) with biochar application under APRDI suggested a reduced risk for N leaching. We conclude that combining biochar application with the APRDI regime could help retain soil N, decrease the risk of N leaching, and enhance crop yield in total for two consecutive planting years. Therefore, this approach is recommended for sustainable N management in long-term planting of perennial crops.

Effect of fertigation frequency on soil nitrogen distribution and tomato yield under alternate partial root-zone drip irrigation

Alternate partial root-zone drip fertigation (ADF) is a combination of alternating irrigation and drip fertigation, with the potential to save water and increase nitrogen (N) fertilizer efficiency. A 2-year greenhouse experiment was conducted to evaluate the effect of different fertigation frequencies on the distribution of soil moisture and nutrients and tomato yield under ADF. The treatments included three ADF frequencies with intervals of 3 (F3), 6 (F6) and 12 days (F12), and conventional drip fertigation as a control (CK), which was fertilized once every 6 days. For the ADF treatments, two drip tapes were placed 10 cm away on each side of the tomato row, and alternate drip irrigation was realized using a manual valve on the distribution tapes. For the CK treatment a drip tape was located close to the roots of the tomato plants. The total N application rate of all treatments was 180 kg ha-1. The total irrigation amounts applied to the CK treatment were 450.6 and 446.1 mm in 2019 and 2020, respectively; and the irrigation amounts applied to the ADF treatments were 60% of those of the CK treatment. The F3 treatment resulted in water and N being distributed mainly in the 0-40-cm soil layer with less water and N being distributed in the 40-60-cm soil layer. The F6 treatment led to 21.0 and 29.0% higher 2-year average mineral N concentration in the 0-20 and 20-40-cm soil layer, respectively and a 23.0% lower N concentration in the 40-60-cm soil layer than in the CK treatment. The 2-year average tomato yields of the F3, F6, F12, and CK treatments were 107.5, 102.6, 87.2, and 98.7 t ha-1, respectively. The tomato yield of F3 was significantly higher (23.3%) than that in the F12 treatment, whereas there was no significant difference between the F3 and F6 treatment. The F6 treatment resulted in yield similar to the CK treatment, indicating that ADF could maintain tomato yield with a 40% saving in water use. Based on the distribution of water and N, and tomato yield, a fertigation frequency of 6 days under ADF should be considered as a water-saving strategy for greenhouse tomato production.

Effects of water and NPK fertigation on watermelon yield, quality, irrigation-water, and nutrient use efficiency under alternate partial root-zone drip irrigation

Alternate partial root-zone drip irrigation (APRD) is efficient in improving irrigation water use efficiency (IWUE). However, little is known about the coupling effects of irrigation and NPK fertilisers on watermelon performance and resource use efficiency under APRD. This study investigated the effects of drip irrigation modes (conventional drip irrigation [CDI], APRD) coupled with NPK fertilisation rates on watermelon growth, IWUE, nutrient use efficiency, yield, and fruit quality. There were five treatments coded as CSH, CDH, CDL, ADH and ADL. The capital letters in the codes indicate drip irrigation modes as CDI (C) or APRD (A), irrigation amount as sufficient (S) or deficit (D, 60% of the total amount of S), and NPK fertilisation rates as high (H) or low (L, 60% of the amount of H). The results showed that compared with CDI at the same fertigation level, APRD increased the photosynthetic rate by 10.1%, plant growth by 25.5%, and NPK absorption by 29.1% across all growth stages, respectively. The promotion effect of APRD was more prominent at early growth stages. APRD increased watermelon yield by 10.4%, thus increased IWUE and fertiliser partial productivity at the same extent, while decreased the NPK use efficiency by 7.0% compared with the CDI counterparts. Compared with CSH, APRD increased vitamin C, total soluble solids (TSS), and the ratio of TSS to total organic acids by 63.2%, 6.2% and 17.2%, respectively. Additionally, the yield didn’t decrease in ADL whereas it increased in ADH, leading to an increase in IWUE of 67.8–78.7% under APRD treatments compared with CSH. Conclusively, APRD could save 40% of total irrigation water and NPK fertilisers without yield reduction while improving fruit quality. Thus, it is suggested as a sustainable practice for watermelon production.

Evaluation of Crop Water Status and Vegetation Dynamics For Alternate Partial Root-Zone Drip Irrigation of Alfalfa: Observation With an UAV Thermal Infrared Imagery

Characterization of the spatiotemporal patterns of crop water status and vegetation dynamics are a prerequisite to overcome water scarcity and obtain precise agricultural water management. Based on high-resolution aerial thermal imagery, we estimated crop water stress index (CWSI), transpiration rate (T), and crop growth status. The research was conducted with conventional subsurface drip irrigation (abbreviated as R) and alternate partial root-zone drip irrigation (abbreviated as P) under four different irrigation quotas: 0 mm, 10 mm, 20 mm, and 30 mm, which are denoted as CK, R10 (P10), R20 (P20), and R30 (P30), respectively. Results indicate that the CWSI is a suitable tool to define alfalfa water status under different irrigation regimes. The CWSI values reflect CK > R10 > R20 > P10 > P20 > R30 > P30, with values of 0.57, 0.41, 0.26, 0.24, 0.18, 0.17, and 0.13, respectively. The T values show that CK < R10 < P10 < R20 < P20 < R30 < P30, with values of 0.46 mm/h, 0.61 mm/h, 0.70 mm/h, 0.71 mm/h, 0.76 mm/h, 0.77 mm/h, and 0.78 mm/h, respectively. In addition, under the same irrigation quotas, the CWSI presented as P10, P20, and P30 was lower than R10, R20, and R30, respectively, while the T was the opposite. Taking the improved transpiration rate as the amount of water saving, it was demonstrated that the alternate partial root-zone drip irrigation was a water-saving method, and each increase of 10 mm in alternating irrigation quotas could save 67.2, 18.4, and 4.6% of water, respectively. This evaluation contributes to a better understanding of the spatiotemporal variations of water and growth status and provides references and theories for the development of modern precise agriculture.

Alternate Partial Root-Zone Drip Nitrogen Fertigation Reduces Residual Nitrate Loss While Improving the Water Use but Not Nitrogen Use Efficiency.

The efficient utilization of irrigation water and nitrogen is of great importance for sustainable agricultural production. Alternate partial root-zone drip irrigation (APRD) is an innovative water-saving drip irrigation technology. However, the coupling effects of water and nitrogen (N) supply under APRD on crop growth, water and N use efficiency, as well as the utilization and fate of residual nitrates accumulated in the soil profile are not clear. A simulated soil column experiment where 30–40 cm soil layer was 15NO3-labeled as residual nitrate was conducted to investigate the coupling effects of different water [sufficient irrigation (W1), two-thirds of the W1(W2)] and N [high level (N1), 50% of N1 (N2)] supplies under different irrigation modes [conventional irrigation (C), APRD (A)] on tomato growth, irrigation water (IWUE) and N use efficiencies (NUE), and the fate of residual N. The results showed that, compared with CW1N1, AW1N1 promoted root growth and nitrogen absorption, and increased tomato yield, while the N absorption and yield did not vary significantly in AW2N1. The N absorption in AW2N2 decreased by 16.1%, while the tomato yield decreased by only 8.8% compared with CW1N1. The highest IWUE appeared in AW2N1, whereas the highest NUE was observed in AW2N2, with no significant difference in NUE between AW2N1 and CW1N1 at the same N supply level. The 15N accumulation peak layer was almost the same as the originally labeled layer under APRD, whereas it moved 10–20 cm downwards under CW1N1. The amount of 15N accumulated in the 0-40 cm layer increased with the decreasing irrigation water and nitrogen supply, with an increase of 82.9–141.1% in APRD compared with that in CW1N1. The utilization of the 15N labeled soil profile by the tomato plants increased by 9–20.5%, whereas the loss rate of 15N from the plant-soil column system decreased by 21.3–50.1% in APRD compared with the CW1N1 treatment. Thus, APRD has great potential in saving irrigation water, facilitating water use while reducing the loss of residual nitrate accumulated in the soil profile, but has no significant effect on the NUE absorbed.

Effects of different nitrogen application rates on dry matter accumulation, distribution and yield of grape under alternate partial root-zone drip irrigation.

To get an optimal mode of irrigation and nitrogen supply for table grape production in North China, a pot experiment was conducted to investigate the effects of different irrigation modes and N application rates on dry matter accumulation and distribution, yield, water use efficiency, and nitrogen use efficiency of table grape. The irrigation modes included conventional drip irrigation (CDI, with sufficient irrigation), alternate partial root-zone drip irrigation (ADI, with 50% amount of the irrigation water of CDI) and fixed partial root-zone drip irrigation (FDI, with 50% amount of the irrigation water of CDI). The nitrogen application rates were set at 0.4 (N1), 0.8 (N2) and 1.2 (N3) g·kg-1 dry soil. The results showed that compared with CDI, ADI and FDI reduced new shoot pruning amount by 34.8% and 11.2%, respectively. New shoot pruning amount increased with increasing N application rates, being highest under CDIN3. Dry matter accumulation of ADI was the highest, being 5.1% and 12.8% higher than CDI and FDI. Dry matter accumulation was higher under N2 and N3 than N1. Compared with CDI and FDI, leaf to fruit ratio reduced but harvest index significantly increased in ADI, while those variables showed no significant difference among diffe-rent N application rates. The ratio of pruning amount to the biomass accumulated in the current year in ADIN2 was the lowest among the treatments. Compared with CDI and FDI, ADI increased grape fruit yield by 6.0% and 10.4%, respectively. Fruit yield was enhanced with increasing nitrogen application rates under the same irrigation condition, with the highest yield under the ADIN2 and ADIN3. Water use efficiency (WUE) increased significantly in ADI compared with CDI and FDI, with the highest value being observed in ADI coupled with N2 or N3. Nitrogen use efficiency (NUE) showed a trend of ADI＞CDI＞FDI. In addition, NUE decreased with increasing nitrogen supply level across the irrigation modes. In conclusion, ADIN2 could reduce the redundant growth of grape tree, promote the transfer of dry matter to fruit, which increased yield and use efficiency of both water and nitrogen, which is a suitable coupling water and nitrogen supply mode for grape production in northern China.

Regulation of soil water threshold on tomato plant growth and fruit quality under alternate partial root-zone drip irrigation

Increasingly limited global freshwater resources coupled with low water use efficiency (WUE) increases the need for water-saving irrigation technologies in agricultural production. Numerous studies have investigated the emerging water-saving irrigation technology of alternate partial root-zone drip irrigation (APDI) on crop yield and WUE. This study investigated the effects of lower soil water thresholds for alteration of the irrigation (LTAI) to the previously dry root-zone on tomato plant growth, yield, and irrigation water use efficiency (IWUE) under APDI in year 2016 with field plot area of 6.48 m2. There were six APDI treatments coded as AS80, AS70, AS60 and AD80, AD70, AD60, indicating APDI under sufficient irrigation (S) or deficit irrigation (D) with LTAI controlled at 80 %, 70 % and 60 % field water capacity (FC) in the previously dry root-zone, respectively. In addition, conventional sufficient (CSD) and deficit (CDD) drip irrigation treatments were added as the controls. The results showed that lowering the irrigation amount significantly reduced tomato plant growth, yield and harvest index, but improved fruit quality in terms of reducing sugar, soluble sugar, vitamin C, and sugar-acid ratio. Compared with that of conventional drip irrigation, the promotion effect of APDI, especially with LTAI at 70 % FC, on root growth was observed in the 0−20 cm top soil layer where more than 90 % of the plant roots were distributed irrespective of irrigation amounts. Under sufficient irrigation, tomato shoot growth and the harvest index showed no significant difference among treatments, but tomato yield and the root to shoot ratio increased significantly in AS70, while fruit quality was improved in AS70 and AS60. Under APDI with deficit irrigation, when LTAI decreased from 80 % FC to 70 % FC in the previously drying root-zone, the yield and IWUE in AD80 and AD70 increased by 8.6 % and 17.4 %, respectively, and thus increased the harvest index compared with CDD. The AD70 treatment saved 31.2 % irrigation water without significant yield reduction, but increased IWUE by 44.9 % compared with the CSD. However, the harvest index and the yield decreased significantly when LTAI decreased from 70 % FC to 60 % FC (AD70 Vs. AD60). In addition, the yield showed no significant difference between AD60 and CDD. Fruit quality increased under APDI as compared with CDD under deficit irrigation, with the best quality appeared in the AD70 and AD60 treatments. These results indicated that the effects of APDI on tomato growth and fruit quality were modulated by LTAI and irrigation amount. APDI with LTAI controlled at 70 % FC was the optimal choice for better yield and fruit quality, especially under deficit irrigation. Unfavorable LTAI could diminish and even eliminate the beneficial effects of APDI on yield and IWUE as compared with conventional drip irrigation.

Alternate partial root-zone drip irrigation with nitrogen fertigation promoted tomato growth, water and fertilizer-nitrogen use efficiency

Irrigation and fertilization play key roles in crop production. Scarcity of available water resources and low nutrient use efficiency calls for a need to improve water and nitrogen (N) use efficiency. This study aimed to investigate the effects of different irrigation and nitrogen treatments on the growth, yield, irrigation water-use efficiency (IWUE) and fertilizer-N utilization of tomato plants by using pre-buried soil columns (100 cm in depth) in a field. The irrigation treatments included conventional drip irrigation (CDI) and alternate partial root-zone drip irrigation (ADI) with sufficient or deficient water supply. Nitrogen fertilizer was set as high and low N input (8.30 g or 4.15 g 15N-labeled urea per plant) supplied as drip fertigation. Compared with the CDI treatment at the same nitrogen drip fertigation level, ADI promoted tomato root growth, induced more 15N accumulation in the 0−100 cm soil profile, facilitated the absorption of fertilizer-15N as well as soil N by plants, thus increasing plant growth and yield as well as IWUE and fertilizer-N use efficiency, while decreased 15N loss. Low nitrogen supply decreased plant growth, yield, 15N absorption, 15N accumulation in soil profile and IWUE, but increased both the 15N-use efficiency and 15N loss percentage. Thus, ADI coupled with nitrogen fertigation has a potential to save irrigation water, increase use efficiencies of both water and nitrogen fertilizers with reduced loss of N to the environment.

Improving Yield and Quality of Processing Tomato (Lycopersicon esculentum Miller) Using Alternate Partial Root-Zone Drip Irrigation in Arid Northwest China

Processing tomato is one of the most important economic crops in Xinjiang, China, which was constrained with severe water shortage and extreme arid climate. Alternate partial root-zone irrigation (APRI) may provide an effective way to increase irrigation water use efficiency (iWUE) without yield reduction. However, limited studies concerned about applying APRI in processing tomato plantation have been done, especially combined with drip irrigation to further control the irrigation and improve iWUE. Therefore, the two-year pot experiments were conducted to study the effects of different irrigation treatments, including three APRI treatments (irrigation quota of 67.5, 51.6, and 43.7 mm, respectively), fixed partial root-zoon drip irrigation (FPRI, 67.5 mm) and conventional drip irrigation (CDI, 67.5 mm). The results indicated that APRI was an appropriate irrigation method in processing tomato plantation in arid desert area such as Xinjiang, as high irrigation quota of APRI (APRIH) significantly improved its yield without fruit quality reduction in comparison with those of CDI. However, the yield without fruit quality of FPRI significantly decreased. Even if the irrigation quota of APRI decreased to the medium level (APRIM, 51.6 mm), iWUE by increased 31.8–32.7% on the contrary, as irrigation water was saved by 23.6%; while keeping the yield and fruit quality. Therefore, APRIM is recommended for processing tomato plantation in arid northwest China, to increase plant growth, fruit quality, yield, and iWUE synergistically.

Tomato yield, quality and water use efficiency under different drip fertigation strategies

Abstract The advantage of alternate partial root-zone drip irrigation combined with ratio of basal N fertilizer to topdressing N fertilizer via drip fertigation on tomato yield, quality and water use remains unresolved. This study has investigated the influences of three drip irrigation methods, including conventional drip irrigation (CDI), alternate partial root-zone drip irrigation (ADI), and fixed partial root-zone drip irrigation (FDI), and five N treatments (N0-100: 100% of N fertilizers as topdressing, N10-90: 10% as basal fertilizer and 90% as topdressing, N20-80: 20% as basal fertilizer and 80% as topdressing, N30-70: 30% as basal fertilizer and 70% as topdressing, and N40-60: 40% as basal fertilizer and 60% as topdressing. All treatments received the same N rate) on tomato yield, quality and water use efficiency, and then the comprehensive quality and comprehensive benefits of different treatments were respectively evaluated by principal component analysis and TOPSIS (technique for order preference by similarity to ideal solution) to obtain optimal water and N supply mode. Compared to CDI, ADI decreased tomato yield slightly, but increased water use efficiency (WUE) by 7.8%, while FDI reduced tomato yield and maintained WUE. In comparison of the five N treatments, N30-70 had higher tomato yield and lycopene and vitamin C contents and sugar/acid ratio in fruits, but it had lower organic acid content in fruits. Among all treatments, ADI-N30-70 had the optimal tomato comprehensive quality and comprehensive benefit. Therefore, ADI-N30-70 was the optimal water and nitrogen supply mode for tomato production in this study.

Alternate partial root-zone drip irrigation improves water\u2013 and nitrogen\u2013 use efficiencies of sweet-waxy maize with nitrogen fertigation

Alternate partial root–zone drip irrigation (ADI) or fertigation has favorable effect on crop water- and nitrogen- use efficiencies (WUE and NUE). However, the advantage of combined application of ADI and nitrogen fertigation on crop WUE and NUE remains unclear. A pot experiment was conducted to investigate the impact of three irrigation methods (CDI conventional drip irrigation (both halves of pot irrigated), ADI (both halves of pot alternatively irrigated) and FDI fixed partial root–zone drip irrigation (fixed half of pot irrigated)) and five nitrogen treatments (F0 no N supplied, F1-F4 0.2, 0.18, 0.16 and 0.14 g N per kg soil via fertigation) on sweet-waxy maize. Compared with CDI, ADI reduced water consumption by 19.9%, but increased water use efficiency based on dry seed yield (WUEs) by 32.3%, and also enhanced nitrogen apparent recovery fraction (Nrf) and nitrogen agronomic efficiency (NAE). F1-F4 augmented dry mass accumulation, dry seed yield and total nitrogen uptake if compared to F0. Moreover, F2-ADI had higher shoot and total dry masses, WUEs, total nitrogen uptake, Nrf and NAE. Thus ADI increased nitrogen uptake, WUE and NUE of sweet-waxy maize with nitrogen fertigation of 0.18 g N per kg soil in this study.

Effect of alternate partial root-zone drip irrigation on soil bacterial communities and tomato yield

The aim of this study was to assess the effect of alternate partial root-zone drip irrigation (ADI) on the soil microbial communities in the crop root zone and the relation between the soil microbial community changes and crop growth. We investigated the effect of ADI at different lower limits of irrigation (ILLs, 50%, 60%, and 70% of the field capacity (FC)) on soil bacterial diversity in the root zone of greenhouse tomato and analyzed the relation between the soil bacterial community changes and tomato growth. The soil bacterial community structure was markedly different under ADI compared with SDI (ground drip irrigation). It was closely related to the soil microenvironment. Among various environmental factors, the tomato root activity, root length, and soil CO2 flux showed significant effects on the difference in soil bacterial communities. Environmental changes in the root-zone soil inevitably affected crop growth, and SDI and ADI resulted in significant differences in root growth, single fruit weight, number of fruits and fruit yield per tomato plant. Our results suggest that an ILL at 70% of the FC could significantly improve the root-zone soil environment, which was beneficial for the organic matter, cellulose, nitrogen and sulfur metabolism and increased the oxygen content in the root-zone soil. Therefore, the root areas, root forks, the fruit number and the yield per plant were better under an ILL at 70% of the FC.

Comparison of dynamic and static APRI-models to simulate soil water dynamics in a vineyard over the growing season under alternate partial root-zone drip irrigation

In this paper, a two-dimensional (2D) dynamic model of root water uptake was proposed based on soil water dynamic and root dynamic distribution of grapevine, and a function of soil evaporation related to soil water content was defined under alternate partial root-zone drip irrigation (APDI). Then the soil water dynamic model of APDI (dynamic APRI-model) was developed on the basis of the 2D dynamic model of root water uptake and soil evaporation function over the growing season. Soil water dynamic in APDI was respectively simulated by dynamic and static APRI-models. The simulated soil water contents by two models were compared with the measured value. Results showed that values of root-mean-square-error (RMSE) for dynamic APRI-model were less than that of the static APRI-model either in the east side or the west side of grapevine. The average relative error between the simulated and measured value was less than 5% for dynamic APRI-model, indicating that the dynamic APRI-model is better than the static APRI-model in simulating the soil moisture dynamic throughout the growing season under the APDI.

Water use efficiency and fruit quality of table grape under alternate partial root-zone drip irrigation

Two-year field experiments were conducted to investigate the effect of alternate partial root-zone drip irrigation on fruit yield, fruit quality and water use efficiency of table grape ( Vitis vinifera L. cv Rizamat) in the arid region of northwest China. Three irrigation treatments were included, i.e. CDI (conventional drip irrigation, both sides of the root-zone irrigated), ADI (alternate drip irrigation, both sides of the root-zone irrigated alternatively with half the water) and FDI (fixed drip irrigation, only one side of the root system irrigated with half the water). Results indicated that compared to CDI, ADI kept the same photosynthetic rate ( P n) but reduced transpiration rate, thus increased leaf water use efficiency (WUE) of table grape. And diurnal variation of leaf water potential showed no significant differences during 7.00 a.m. to 14.00 p.m. in both years. ADI also produced similar yield and improved WUE ET by 26.7–46.4% and increased the percentage of edible grape by 3.88–5.78%, vitamin C content in the fruit by 15.3–42.2% and ratio of total soluble solid concentration/titrated acid in both years as compared to CDI. Thus ADI saved irrigation water, improved the water use efficiency and fruit quality of table grape without detrimental effect on the fruit yield in arid region.

Water use and yield responses of cotton to alternate partial root-zone drip irrigation in the arid area of north-west China

A field experiment was carried out over 2 years to investigate the effect of partial root-zone irrigation applied using drip irrigation on the water use and yield of cotton (Gossypium hirsutum) in oasis fields of arid north-west China. Two irrigation treatments, i.e., conventional drip irrigation (CDI, both sides of plant row watered) or alternate drip irrigation (ADI, both sides of plant row alternatively watered) were applied under plastic mulch. Three irrigation levels (i.e., 15, 22.5, 30 mm during 2004 and 12, 18, 24 mm during 2005) were applied at each irrigation. Monitoring of soil water contents in the ADI treatment indicated a change in root-zone uptake in response to the irrigation method, although there existed some lateral soil water movement from the wetted side to the dry side after each watering. Stomatal conductance in ADI was lower than that of CDI when compared at the same irrigation level. Reduced stomatal conductance and water loss resulted in higher water use efficiency (WUE) in the ADI treatment. About 31-33% less total irrigation water was applied using the ADI method when compared to that of the CDI treatment with a similar seed cotton yield. ADI also yielded 11% more pre-frost seed cotton than CDI in 2005, indicating a better lint quality and higher price. These results suggest that ADI should be a useful water-saving irrigation method in arid oasis fields where cotton production is heavily dependent on irrigation and water resources are scarce.

Comparison of APRI and Hydrus-2D models to simulate soil water dynamics in a vineyard under alternate partial root zone drip irrigation

Alternate partial root zone irrigation (APRI) is a new water-saving irrigation technique. It can reduce irrigation water and transpiration without reduction in crop yield, thus increase water and nutrient use efficiency. Understanding of soil moisture distribution and dynamic under the alternate partial root zone drip irrigation (APDI) can help to develop the efficient irrigation schemes. In this paper, a two-dimensional (2D) root water uptake model was proposed based on soil water dynamic and root distribution of grape vine, and a function of soil evaporation related to soil water content was defined under the APDI. Then the soil water dynamic model of APDI (APRI-model) was developed based on the 2D root water uptake model and soil evaporation function combined with average measured soil moisture content at 0–10 cm soil layer. Soil water dynamic in APDI was respectively simulated by Hydrus-2D model and APRI-model. The simulated soil water contents by two models were compared with the measured value. The results showed that the values of root-mean-square-error (RMSE) range from 0.01 to 0.022 cm3/cm3 for APRI-model, and from 0.012 to 0.031 cm3/cm3 for Hydrus-2D model. The average relative error between the simulated and measured soil water content is about 10% for APRI-model, and from 11% to 29% for Hydrus-2D model, indicating that two models perform well in simulating soil moisture dynamic under the APDI, but the APRI-model is more suitable for modeling the soil water dynamic in the arid region with greater soil evaporation and uneven root distribution.