Conventional Flood Irrigation Research Articles

Unraveling nitrogen loss in paddy soils: A study of anaerobic nitrogen transformation in response to various irrigation practice

Soil nitrogen (N) transformation processes, encompassing denitrification, anaerobic ammonium oxidation (anammox), and anaerobic ammonium oxidation coupled with iron reduction (Feammox), constitute the primary mechanisms of soil dinitrogen (N2) loss. Despite the significance of these processes, there is a notable gap in research regarding the assessment of managed fertilization and irrigation impacts on anaerobic N transformations in paddy soil, crucial for achieving sustainable soil fertility management. This study addressed the gap by investigating the contributions of soil denitrification, anammox, and Feammox to N2 loss in paddy soil across varying soil depths, employing different fertilization and irrigation practices by utilizing N stable isotope technique for comprehensive insights. The results showed that anaerobic N transformation processes decreased with increasing soil depth under alternate wetting and drying (AWD) irrigation, but increased with the increasing soil depth under conventional continuous flooding (CF) irrigation. The denitrification and anammox rates varied from 0.41 to 2.12 mg N kg−1 d−1 and 0.062–0.394 mg N kg−1 d−1, respectively, which accounted for 84.3–88.1% and 11.8–15.7% of the total soil N2 loss. Significant correlations were found among denitrification rate and anammox rate (r = 0.986, p < 0.01), Fe (Ⅲ) reduction rate and denitrification rate (r = 0.527, p < 0.05), and Fe(Ⅲ) reduction rate and anammox rate (r = 0.622, p < 0.05). Moreover, nitrogen loss was more pronounced in the surface layer of the paddy soil compared to the deep layer. The study revealed that denitrification predominantly contributed to N loss in the surface soil, while Feammox emerged as a significant N loss pathway at depths ranging from 20 to 40 cm, accounting for up to 26.1% of the N loss. It was concluded that fertilization, irrigation, and soil depth significantly influenced anaerobic N transformation processes. In addition, the CF irrigation practice is best option to reduce N loss under managed fertilization. Furthermore, the role of microbial communities and their response to varying soil depths, fertilization practices, and irrigation methods could enhance our understanding on nitrogen loss pathways should be explored in future study.

Response of Soil Nitrogen Components and nirK- and nirS-Type Denitrifying Bacterial Community Structures to Drip Irrigation Systems in the Semi-Arid Area of Northeast China

Denitrification is a key process in soil available nitrogen (N) loss. However, the effects of different water-saving irrigation systems on soil N components and denitrifying bacterial communities are still unclear. In this study, quantitative fluorescence PCR and Illumina MiSeq sequencing were used to investigate the effects of three main irrigation systems, conventional flooding irrigation (FP), shallow buried drip irrigation (DI), and mulched drip irrigation (MF), on the abundance, community composition, and diversity of soil nirK- and nirS-type denitrifying bacteria in the semi-arid area of Northeast China, and to clarify the driving factors of nirK- and nirS-type denitrifying bacterial community variations. The results showed that, compared with FP, MF significantly increased soil moisture, alkaline hydrolyzed nitrogen (AHN), nitrate nitrogen (NO3−-N), non-acid hydrolyzed nitrogen (AIN), and amino sugar nitrogen (ASN), but significantly decreased the contents of ammonium nitrogen (NH4+-N) and acid hydrolyzed ammonium nitrogen (AN). The irrigation system changed the relative abundance of the dominant genera of denitrifying bacteria, DI and MF significantly increased nitrate reductase (NR) and nitrite reductase (NiR) activities, and MF significantly increased the diversity of nirK- and nirS-type denitrifying bacteria but significantly decreased the richness. The community structure of nirK- and nirS-type denitrifying bacteria was significantly different among the three irrigation systems. NO3−-N was the main driving factor affecting the community structure of nirS-type denitrifying bacteria, and moisture significantly affected the community structure of nirK-type denitrifying bacteria. DI and MF significantly increased the abundance of nirK- and nirS-type denitrifying bacteria and also increased the abundance ratio of nirS/nirK genes. Therefore, although DI and MF significantly increased the abundance of denitrifying microorganisms, they did not lead to an increase in the N2O emission potential.

Recent impacts of water management on dryland’s salinization and degradation neutralization

Reducing soil salinization of croplands with optimized irrigation and water management is essential to achieve land degradation neutralization (LDN). The effectiveness and sustainability of various irrigation and water management measures to reduce basin-scale salinization remain uncertain. Here we used remote sensing to estimate the soil salinity of arid croplands from 1984 to 2021. We then use Bayesian network analysis to compare the spatial–temporal response of salinity to water management, including various irrigation and drainage methods, in ten large arid river basins: Nile, Tigris-Euphrates, Indus, Tarim, Amu, Ili, Syr, Junggar, Colorado, and San Joaquin. In basins at more advanced phases of development, managers implemented drip and groundwater irrigation and thus effectively controlled salinity by lowering groundwater levels. For the remaining basins using conventional flood irrigation, economic development and policies are crucial for establishing a virtuous circle of “improving irrigation systems, reducing salinity, and increasing agricultural incomes” which is necessary to achieve LDN.

The effect of alternate partial root-zone drying and deficit irrigation on the yield, quality, and physiochemical parameters of milled rice

While paddy fields produce a high yield, they also require a large amount of water and produce a significant amount of methane. Therefore, the adoption of water-saving irrigation techniques for rice cultivation is critical. Furrowed rice farming may be a viable alternative to paddy rice cultivation. The objective of the present study was to evaluate the impact of alternate partial root-zone drying irrigation on rice yield, milled rice quality, and cooking quality under furrow rice cultivation. A two-year field trial was conducted on a local rice cultivar, Tarom Hashemi, in 2015 and 2016. Seven water regimes, including three levels of regulated deficit irrigation (RDI), three levels of alternate partial root-zone drying irrigation (APRDI), and conventional flooding irrigation (CFI), were used in this study. In RDI and APRDI treatments, plots were irrigated when soil matric potential had reached −0.1 (RDI1 and APRDI1), −0.3 (RDI3 and APRDI3), and −0.6 bar (RDI6 and APRDI6). RDI1 and APRDI1 treatments produced milled rice yield similar to the CFI, while irrigation water productivity (IWP) was significantly higher by 22.9% and 45.7%, respectively. Regardless of the soil water potential, the IWP in APRDI treatments was 16% higher than that of RDI treatments. Severe water stress (RDI6 and APRDI6) caused a marked increase in amylose content and alkali spreading value of milled rice resulting in improved cooking quality. Nitrogen uptake in APRDI treatments was 2% higher than that of RDI treatments. On average, methane emission per milled grain yield declined by 77.9% and 78.7% in RDI and APRDI treatments, respectively. Our data indicate that the expensive and laborious practice of puddling can be avoided to increase water productivity and improve rice quality without sacrificing yield. The results also show that furrow rice cultivation could significantly reduce the methane emission contribution of rice production.

Comparative Analysis of Growth and Physiological Responses of Sugarcane Elite Genotypes to Water Stress and Sandy Loam Soils.

Stumpy irrigation water availability is extremely important for sugarcane production in Pakistan today. This issue is rising inversely to river flow due to inadequate water distribution and an uneven rainfall pattern. Sugarcane growth faces a shortage of available water for plant uptake due to the low water-holding capacity of sandy loam soil, particularly under conventional flood irrigation methods. To address this problem, sugarcane clones were evaluated for their agronomic and physiological traits under conditions of low water availability in sandy loam soil. Ten cane genotypes, HSF-240, SPF-213, CPF-249, CP 77-400, S2008-FD-19, S2006-US-469, S2007-AUS-384, S2003-US-633, S2003-US-127, and S2006-US-658, were exposed to four levels of water deficit created through skip irrigations. These deficit levels occurred during the 9th, 11th, 13th, and 16th irrigations at alternate deficit levels between 2020 and 2022. Physiological data were collected during the tillering and grand growth stages (elongation) in response to the water deficit. The sugarcane clones S2006-US-658, S2007-AUS-384, and HSF-240 exhibited resistance to low water availability at both the tillering and grand growth stages. Following them, genotypes S2006-US-658, S2007-AUS-384, and HSF-240 performed better and were also found to be statistically significant. Clones susceptible to water deficit in terms of growth and development were identified as CP 77-400, S2008-FD-19, S2006-US-469, and S2003-US-633. These genotypes showed reduced photosynthetic rate, transpiration rate, stomatal conductance, relative water content, cane yield, and proline content under stressed conditions. Therefore, genotypes S2006-US-658, S2007-AUS-384, and HSF-240 were better performers concerning physiological traits under water deficit and sandy loam soil in both years. Moreover, a significant positive correlation was assessed between agronomic traits and photosynthetic rats. This study highlights that sugarcane can sustain its growth and development even with less irrigation frequency or moisture availability, albeit with certain specific variations.

Tillage Crop Establishment and Irrigation Methods Improve the Productivity of Wheat (Triticum aestivum): Water Use Studies, and the Biological Properties and Fertility Status of Soil

The Crop Research Centre of Sardar Vallabhbhai Patel University of Agriculture and Technology in Meerut (U.P.), India, conducted field experiments in a randomised block design, comprising three replicates, one late sown variety (DBW-90), and eight treatments, viz.: T1 was a conventional flood irrigation (CFI); T2, furrow irrigated with gated-pipe raised beds (FIGPRB); T3, all furrow irrigation (AFI); T4, alternate furrow irrigation (Alt. FI); T5, wide bed furrow irrigation (WBFI); T6, skip furrow irrigated (SFI); T7, Sprinkler irrigation (SI); and T8, Zero-till flat-irrigated using gated pipe/controlled-flood irrigation (ZTFIGP). These field experiments were conducted during the Rabi seasons of 2017–2018 and 2018–2019. The purpose of this study was to evaluate the yield, water productivity, and soil health under different tillage crop establishment methods. Test weight, spike length, and productive tillers were all considerably enhanced in treatment T5, with the treatment’s statistical significance being similar to that of treatments T8 and T2. Treatment T5 considerably outperformed the other treatments in terms of grain yield, straw yield, biological yield (44.32, 61.88, and 106.19 q ha−1, respectively), as well as harvest index (41.73). Thirty to sixty centimetres of soil were mined for the most water, followed by fifteen to thirty centimetres, zero to fifteen centimetres, and sixty to ninety centimetres. Both water-use efficiency (2.86 q ha−1 cm) and water productivity (1.91 kg cm−3) were highest under T7 (Sprinkler irrigation). The maximum total NPK (113.69; 27.45; 127.33 kg ha−1) was found in crops grown with wide bed furrow irrigation. The data also showed that treatment T6 (skip furrow irrigated) had the highest levels of accessible NPK in soil, followed closely by treatment T4 (alternate furrow irrigated). Treatment T8 (zero-till flat-irrigated using gated-pipe/controlled flood irrigation) had the highest bacterial, fungal, and actinomycete populations, followed by T5 (wide bed furrow irrigated) and T2 (furrow irrigated with gated-pipe/elevated bed). Our research showed that there may be more options for maintaining wheat crop water productivity and soil health under different agroecological conditions, including crop productivity, conservation tillage-based establishing methods, and irrigation regimes.

Effect of N and P fertigation on fruit yield and quality of kinnow

The effects of N and P fertigation on productivity and quality of kinnow mandarin were investigated in southwestern part of Punjab at the Regional Research Station, Abohar of Punjab Agricultural University, Ludhiana, Punjab during 2018–2020. Different combinations of the recommended dose (RD) of N and P, viz. 100, 75, and 50% were applied in equal splits at 5 stages of kinnow trees (February–October) and compared with conventional flood irrigation plus soil fertilization. The results showed that fertigation resulted in higher nutrient uptake, total leaf chlorophyll content, and vital physiological processes as compared to conventional practices. Tree volume under fertigation was about 29% higher than conventional practices. The data also revealed a significantly higher fruit set (20.13%), fruit weight (168.6 g), and fruit size (7.68 cm) as compared to flood irrigation plus soil fertilization. Fruit yield was about 33% higher in fertigated trees over flood irrigation and soil fertilization. Further, fruit quality parameters especially in terms of per cent juice, TSS-acid ratio, and ascorbic acid concentration were also superior in fertigated trees. In addition, fertigation resulted in a higher proportion of economic fruit grades over conventional flood irrigation and soil fertilization. The results suggest that fertigation @75% of N and P of recommended dose exhibited higher growth and productivity of kinnow mandarin, saving 25% N and P usage with better grade andhigher quality of kinnow.

Drip fertigation with straw incorporation promotes soil microbial network complexity and potentially reduces pathogen abundance in greenhouse vegetable production systems

Continuous monoculture, conventional flood fertigation and low soil fertility increase the risk of soil-borne diseases in greenhouse vegetable production systems. Drip fertigation with straw incorporation (DIF+S) significantly improves resource use efficiency and reduces environmental risks compared to conventional fertigation. However, it remains unclear whether DIF+S positively affects soil microbial diversity and community structure and reduces the occurrence of soil-borne diseases. Therefore, a two-factor field trial was conducted in a greenhouse tomato production system with drip vs. flood fertigation, with and without straw incorporation across the seven growing seasons. The experimental treatments were as follows: (i) conventional flood irrigation with overfertilization (CIF); (ii) CIF + straw incorporation; (iii) drip fertigation with reduced irrigation and fertilization (DIF); and (iv) DIF + straw incorporation. Across the seven growing seasons, the average water and nitrogen use efficiency (WUE and NUE) was two- and threefold higher for DIF than for CIF, respectively, whereas tomato yields remained high. DIF significantly increased soil bacterial diversity and network complexity compared to CIF but had no effect on the soil fungal community. DIF significantly reduced the relative abundance of Fusarium-induced tomato wilt. Moreover, straw application significantly decreased fungal diversity while increasing fungal network complexity, although no effect on the bacterial community was found. The relative abundance of plant pathogens, such as Cladosporium, Fusarium and Alternaria, which are related to soil-borne diseases of tomato plants, was significantly reduced when straw was incorporated. Our results highlight that drip fertigation combined with straw incorporation significantly positively affects soil microbial diversity and stability. Thus, DIF+S is a sustainable and effective technology for maintaining soil health and reducing pesticide use in greenhouse vegetable production systems.

The Effect of Deep Placement of Basal Nitrogen Fertilizer on Gaseous Nitrogen Losses and Nitrogen Use Efficiency of Paddy Fields under Water-Saving Irrigation in Northeast China

As a widely implemented irrigation regime for paddy fields, water-saving irrigation (WSI) is capable of ensuring water resource security and improving nitrogen use efficiency (NUE). Higher gaseous nitrogen losses (GNL) lead to a low recovery rate of basal nitrogen, and this is the primary reason that restricts further improvements in the NUE under WSI. The deep placement of nitrogen fertilizer (DPN) is considered an efficient agricultural management measure to reduce GNL. However, the effects of WSI combined with the deep placement of basal nitrogen fertilizer on NUE, GNL, and rice yield in paddy fields remain largely unknown. In this study, a 2-year field experiment was conducted to measure GNL (N2O emissions and NH3 volatilization), NUE, and rice yield. Four treatments were utilized: (i) conventional flooding irrigation + broadcast of nitrogen fertilizer (110 kg N hm−2, CFN); (ii) water-saving irrigation + deep placement of basal nitrogen fertilizer (110 kg N hm−2, WSN); (iii) water-saving irrigation + deep placement of basal nitrogen fertilizer (99 kg N hm−2, WSN1); (iv) water-saving irrigation + deep placement of basal nitrogen fertilizer (88 kg N hm−2, WSN2). The results showed that the GNL in paddy fields under treatment ranged from 5.29 to 10.67 kg hm−2. Deep placement of basal nitrogen fertilizer mitigated the GNL of the paddy fields under WSI. The GNL of CFN was significantly higher than those of WSN1 and WSN2 by 26.9% and 54.0% in 2021 and 14.4% and 23.3% in 2022, respectively (p &lt; 0.05). Under WSI, the deep placement of basal nitrogen fertilizer reduced the GNL primarily via the reduction of NH3 volatilization. NH3-N of CFN was higher than those treatments under WSI. The rice yield of CFN was significantly lower than those of WSN and WSN1 by 22.4% and 21.6% in 2021 and 4.6% and 1.5% in 2022, respectively. (p &lt; 0.05). Moreover, the NUE of each treatment under WSI was higher than that of CFN. These changes exhibited similar trends in 2021 and 2022. These results demonstrated that deep placement of basal nitrogen fertilizer is an effective practice to ensure food and environmental security under WSI.

The Response of Grain Yield and Quality of Water-Saving and Drought-Resistant Rice to Irrigation Regimes

Of all the crops, rice is the one that consumes the most water. Rice yields and quality are significantly influenced by irrigation. However, it is still unknown how different irrigation practices would affect the grain yield and quality of water-saving and drought-resistant rice. Hyou 518 (high-yielding rice variety) and Hanyou 73 (water-saving and drought-resistant rice variety) were employed as materials. Three irrigation regimes were set up in the field: conventional flooding irrigation (CF), alternate wetting and moderate soil drying irrigation (AWD), and dry cultivation (D). It was investigated how various irrigation regimes affected the two varieties’ yield and quality. The results revealed the following: 1. D considerably increased water-use efficiency while drastically reducing the yield, compared to CF and AWD. In comparison to other irrigation regimes, the grain yield and water use efficiency of Hanyou 73 enhanced synergistically under AWD treatment. 2. In contrast to CF treatment, AWD and D (especially) treatments decreased perfect rice kernel, total starch content, amylose content, amylopectin content, amylose/amylopectin, gel consistency, and breakdown, but increased green rice kernel, chalky kernel, protein content, and setback. 3. After heading, AWD and D lowered, and D treatment decreased more, the activities of ADP-glucose pyrophosphorylase (AGP), soluble starch synthase (SSS), and starch branching enzyme (SBE). AGP, SSS, and SBE were strongly inversely linked with perfect rice kernel, amylopectin content, gel consistency, and breakdown, but significantly negatively correlated with green rice kernel, chalky kernel, protein content, and setback. The results indicate that with AWD treatment, Hanyou 73 might provide a synergistic boost grain production, water-use efficiency, and quality. D treatment could significantly improve water-use efficiency. Compared with Hyou518, Hanyou 73 could maintain higher AGP, SSS, and SBE activities, head milled rice, perfect rice kernel, amylopectin content, and gel consistency under AWD and D treatment.

Effects of sub-surface wick irrigation system on crop yield, irrigation intervals, base period and crop water productivity of sponge gourd and bitter gourd.

Abstract A field experiment was conducted on a clayey soil, during winter season of October 2022 to January 2023, at the experimental field of Department of Land and Water Management, Faculty of Agricultural Engineering, Sindh Agriculture University Tandojam on an area of 28m 2 , to evaluate the effects of sub-surface wick irrigation system on yield, irrigation intervals and crop water productivity (CWP) on sponge gourd ( Luffa aegyptiaca ) and Bitter Gourd ( Momordica charantia ) Crops. For burying wick attached bottles total 6 basins were prepared by cultivating the soil down to 60 cm with hand hoe; basin to basin distance was 2m. After that, wick attached bottles were buried 25-30 cm bellow the bed of the basins. The water holding capacity of each bottle was 2.25 liter, every bottle was cut from tail end for water filling purpose, and it also serves as covering lid to avoid evaporation losses. 3 basins were used for growing Sponge Gourd ( Luffa aegyptiaca ) with quality of irrigation water (1.47 dS/m) and other 3 for Bitter Gourd ( Momordica charantia ) crops with same irrigation water properties. 4 seeds of sponge gourd bitter gourd were buried at the depth of 2-5 cm around each basin. Bottles were refilled each time when they reached at a depletion level of 75%. Experimental design was randomized complete block design (RCBD) with two treatments: (1) Wick irrigation system for sponge gourd from Basin1 to 3 (WS) and Wick irrigation system for bitter gourd from basin 4 to 6 (WB). The results of the experiment revealed that the base period of sponge gourd crop was 95 days with 28 irrigation intervals, while the base period of bitter gourd was 102 days with 31 irrigation intervals. Average yield was achieved 3.64 kg/basin (10.03 ton/ha -1 ) with WS, 4.16 kg/basin (11.46 ton/ha -1 ) with WB treatments, respectively. The crop water productivity (CWP) of sponge gourd under WS was 13.86 kg/m 3 and 19.66 kg/m 3 for bitter gourd under WB treatments respectively. Base period was significantly increased by 20 to 30 days for both crops with wick irrigation system as compared to conventional flood irrigation systems. The study suggests that this system in not properly adopted or well understood by users, therefore it needs further improvement so that, the farmers can take more benefits and to make it more capable for large scales farming.

Water saving and crop yield under sub-surface wick irrigation system for sponge gourd ( Luffa aegyptiaca ) and bitter gourd ( Momordica charantia ) crops.

Abstract High Efficiency Irrigation Systems (HEIS) are expensive to install maintain and cannot be operated without skillful labor. While, new water conserving micro irrigation technologies are becoming more popular in counties where water is almost negligible for adopting flood or other conventional irrigation techniques, these technologies can be adopted to convert the desert land into oasis. The present study was thus conducted on experimental field of Department of Land and Water Management, Faculty of Agricultural Engineering, Sindh Agriculture University Tandojam to evaluate the performance of sub-surface bottle wick irrigation system in terms of water saving and crop yield. Total twelve plastic bottles with water holding capacity of 2 liters were used in the study. All bottles are drilled at the opening caps; wicks were fixed in these holes and glued. Treatments were named as, wick irrigation system for sponge gourd (WS) and wick irrigation system for bitter gourd (WB). Total 6 basins were used in this study and named as B1 to B6 (B1-B3 used for WS and B4-B6 for WB treatments), 2 wicks attached plastic bottles were buried in basins at 10-15 cm bellow the soil surface and the irrigation was applied. The sponge and bitter gourd overnight wetted seeds were sown on the wetted soil around the wicks. The experimental results revealed that the water savings were about 90.1%, and 92.5% with WS and WB treatments respectively, compared to conventional flood irrigation systems. The crop yield was 3.64 kg/basin (9100 kg/hac -1 ) and 4.16 kg/basin (10400 kg/hac -1 ) with WS and WB treatments. The crop water productivity (CWP) was about 13.68 kg/m 3 and 19.66 kg/m 3 with WS and WB treatments. It was concluded that wick irrigation system performs better, especially in terms of water saving and crop yield, but it need several irrigation intervals and consume more time. Further, studies may be conducted on different aspects with different crops and different soil textures. Users are suggested to adapt wick irrigation in water scare regions, small scale farming, urban agriculture, green house crop production. If irrigation is available in large amount, flood irrigation systems can be used to achieve higher yields.

Experimental Evaluation of Irrigation Methods for Yield, Water Productivity, and Economics of Paddy-Wheat Cropping System under Conservation Agriculture

Irrigation methods have critical role in increasing the water productivity and crop production under paddy-wheat cropping systems. An experiment was carried out at Ludhiana, Punjab, India, in a randomized block design with eight treatments on drip and flood irrigation systems under conventional and conservation agricultural practices. Under conservation agriculture practice, drip irrigation had six treatments with different combinations of dripline spacing × emitter spacing × dripline depth as 675 × 300 × 0 mm (T1), 450 × 400 × 0 mm (T2), 675 × 300 × 150 mm (T3), 450 × 400 × 150 mm (T4), 675 × 300 × 200 mm (T5), 450 × 400 × 200 mm (T6). The treatments on conventional flood irrigation method included crop cultivation under farmer’s practice (T7) and under conservation agriculture practice (T8). The treatment T4 recorded significantly higher grain yield of wheat (6.522 t.ha-1) and paddy (8.178 t.ha-1) and water productivity (3.73, 1.20 kg.m-3, respectively. In the root zone of both wheat and paddy crops, the drip irrigation systems recorded lowest soil moisture variation within 0-450 mm soil depth under treatment T4 (4.33% to 9.77%), while it was highest under T7 (10.38% to 40.41%). The treatment T4 also showed water saving of 55.3% over the conventional flood irrigation method under paddy-wheat cropping system. In economic terms, the treatment T4 performed better with a benefit-cost ratio of 3.15 under the condition that 95% subsidy is availed on cost of drip irrigation system.

Drip fertigation with treated municipal wastewater and soil amendment with composted sewage sludge for sustainable protein-rich rice cultivation

Rice paddy farming is threatened by global water scarcity, necessitating the adoption of novel water-saving cultivation practices. The purpose of this study is to determine the effects of drip fertigation with treated municipal wastewater (TWW) on a rice–soilsystem that is amended with composted sewage sludge (CSS). The treatments included flood irrigation with tap water (Control; T1), flood irrigation with TWW (T2), drip irrigation (DI) with TWW at 86% water consumption (T3), DI with TWW at 75% water consumption (T4), DI with TWW at 69% water consumption (T5), and DI with tap water at 86% water consumption (T6). The control was administered mineral fertilizers, and all other treatments received the same N amount (260 kg ha −1 ) from CSS. The results indicated that TWW drip fertigation had a significant beneficial effect on rice production by increasing (59.7 g pot −1 , T3) or maintaining (51.4 g pot −1 , T4) grain yield while conserving up to 25% of water when compared to conventional flood irrigation and mineral fertilizer application (52.9 g pot −1 ). In comparison to conventional farming, TWW drip fertigation in conjunction with CSS amendment significantly increased grain protein and Cu content while reducing As accumulation by 50%. Both CSS and TWW are effective at retaining soil fertility while avoiding unfavorable accumulation of As, Pb, Cd, Cu, and Zn. The novel cultivation techniques described herein have the potential to significantly improve the sustainability of rice farming in water-stressed areas, as well as integrated wastewater management strategies aimed at achieving sustainable development goals. • Rice farming can benefit from treated wastewater (TWW) and composted sludge (CSS). • TWW drip fertigation greatly increased rice yield and conserved up to 25% of water. • CSS and TWW reuse increased protein while lowering As contents by 50% in grains. • The practices effectively preserved soil fertility without toxic element buildup.

Alternate wetting and moderate soil drying could increase grain yields in both main and ratoon rice crops

AbstractAlternate wetting and drying irrigation is a widely used irrigation method for water‐savings and high‐yielding in rice (Oryza sativa L.) production; however, its effect on grain yield (GY) in the main and ratoon crops is unclear. With two rice cultivars as materials, the effects on GY in the main and ratoon crop of three irrigation regimes, that is, conventional flooding irrigation (CI), alternate wetting and moderate soil drying irrigation (WMD), and alternate wetting and severe soil drying irrigation (WSD), during grain filling of the main crop were investigated. Compared with CI, WMD increased GY by 6.0∼6.5% in the main crop by increasing the 1,000‐grain weight and filled grain rate, whereas the ratoon crop GY increased by 13.3∼14.6% via increased panicle number. The WSD had no significant effects on the main crop GY, but significantly decreased ratoon crop GY by decreasing panicle number. A higher leaf photosynthetic rate, leaf area index, root oxidation activity, dry matter accumulation and nonstructural carbohydrate (NSC) translocation under WMD primarily drove the increased 1,000‐grain weight and filled grain rate in the main crop. Under WMD, higher soluble sugar contents catalysed by high amylase activity and higher zeatin + zeatin riboside in stems of the main crop promoted the growth of regenerated buds and increased the ratoon crop panicle number. In conclusion, WMD during grain filling of the main crop improved the growth and development of the main crop and promote the germination of regenerated buds, thereby increasing the GY of both main and ratoon crops.

Effect of Irrigation and Fertilizer Management on Rice Yield and Nitrogen Loss: A Meta-Analysis.

Irrigation and nitrogen fertilizer application are two important factors affecting yield and nitrogen loss in rice fields; however, the interaction effects of different irrigation schedules and combined management of nitrogen fertilizer application on yield and nitrogen loss in rice fields remain unknown. Therefore, we collected 327 sets of data on rice yield and 437 sets of data on nitrogen loss in rice fields from 2000 to 2021 and investigated the effects of different water-saving irrigation schedules, nitrogen application levels, and water–nitrogen couplings on rice yield, nitrogen use efficiency, and nitrogen loss (N2O emissions, nitrogen runoff, nitrogen leaching, and ammonia volatilization) by meta-analysis using conventional flooding irrigation and no nitrogen treatment as controls. The results showed that alternate wet and dry irrigation and controlled irrigation had increasing effects on rice yield. Alternate wet and dry irrigation had a significant yield-increasing effect (average 2.57% increase) and dry cultivation significantly reduced rice yield with an average 21.25% yield reduction. Water-saving irrigation reduces nitrogen runoff and leaching losses from rice fields but increases N2O emissions, and alternate wet and dry irrigation has a significant effect on increasing N2O emissions, with an average increase of 67.77%. Most water-saving irrigation can increase nitrogen use efficiency. Among water-saving irrigation methods, the effect of controlled irrigation on increasing nitrogen use efficiency is 1.06%. Rice yield and nitrogen use efficiency both showed a trend of increasing then decreasing with nitrogen fertilizer application, and nitrogen loss gradually increased with the amount of nitrogen fertilizer input. Water–nitrogen coupling management can significantly reduce nitrogen loss in rice fields while saving water and increasing yield. Based on the analysis of the data in this study, when the irrigation amount was 300~350 mm and the nitrogen application amount was 200~250 kg/ha, the rice yield and nitrogen fertilizer use efficiency were at a high level, which corresponded to the irrigation schedule of controlled irrigation or alternating wet and dry irrigation in the literature. However, different rice-growing areas are affected by rainfall and land capability, etc. Further optimization and correction of the adapted water and fertilizer management system for paddy fields are needed. The optimal water–nitrogen pattern of this study can achieve high rice yield and reduce nitrogen loss.

Alternate wetting–drying enhances soil nitrogen availability by altering organic nitrogen partitioning in rice-microbe system

Alternate wetting and drying (AWD) irrigation influences soil nutrient cycling and the functioning of soil microorganisms. However, the effects of AWD on organic nitrogen (ON) partitioning in rice-microbe ecosystems and soil microbial communities are poorly understood. A root-box microcosm experiment with two rice varieties (Nipponbare, Nip; Yangdao 6, YD6), two irrigation regimes (conventional flood irrigation (CF); AWD) and three N application levels (zero N, N0; medium N, N1; high N, N2) was performed based on the 13C,15N-labelled glycine and 13C-phospholipid fatty acids (PLFA) techniques. Compared to CF, AWD increased soil dissolved oxygen, microbial growth and the enzymes related to N transformation, thus enhancing rice growth and the N utilization index (NUI). Approximately 4.9–10.3% and 7.7–13.6% of the exogenous glycine was directly utilized by Nip and YD6 seedlings, respectively, and its ratio increased with increasing N levels, whereas 4.4–11.2% and 4.6–10.3% were incorporated into soil microbes. It seems that rice has an appreciable capacity to utilize organic N despite fierce competition with soil microbes. The 13C:15N ratio showed that 12.5–37.5% and 11.0–41.0% of the added glycine was taken up intact by soil microorganisms in the rhizospheres of Nip and YD6. At the N1 and N2 levels, AWD increased rice 15N-glycine uptake but decreased microbial 15N-glycine uptake. Rice intact glycine uptake and soil inorganic N contents were positively correlated with rice biomass and NUI, indicating that the enhanced inorganic N under AWD is beneficial for soil ON availability and rice growth. Gram-negative and general bacteria were the dominant competitors with rice for soil ON. AWD increased the contents of gram-negative bacteria and fungi and the ratio of fungi:bacteria in rhizosphere soils. Collectively, AWD creates a good rhizosphere oxygen environment for rice and microbial growth. ON partitioning in the rice-microbe system and the adaptive adjustment of the microbial community play important roles in modulating soil nutrients for optimal rice growth.

Effects of irrigation methods on transpiration and water use efficiency of tomato

Objective: To explore the effect of high-frequency drip irrigation on the physiological water savings of facility tomatoes. Methods: A pot experiment was conducted to study the effects and mechanisms of conventional flood irrigation (CFI) and high-frequency drip irrigation (HDI) on the transpiration and water use efficiency of tomatoes. Results: a. During the whole growth period, the irrigation times of high-frequency drip irrigation were 44 times, which was 3.4 times of traditional flood irrigation, and the irrigation amount was only 71.0% of flood irrigation. However, there was no significant difference in fruit, stem, or leaf dry weight between the two treatments (&lt;em&gt;p&lt;/em&gt; &amp;gt; 0.05). b. The average transpiration of tomatoes under high-frequency drip irrigation was 28.95 L/plant, which was significantly lower than that under traditional flood irrigation by 24.6%. c. Compared with conventional flood irrigation, high-frequency drip irrigation treatment significantly increased irrigation water use efficiency (biomass/irrigation volume) and water physiological use efficiency (biomass/transpiration volume) by 21.2% and 14.2%, respectively (&lt;em&gt;p&lt;/em&gt; &amp;lt; 0.05). d. Compared with conventional flood irrigation, high-frequency drip irrigation significantly decreased tomato leaf area, stomatal conductance, and transpiration rate by 32.6%, 69.8%, and 54.3%, respectively, and significantly increased leaf δ&lt;sup&gt;13&lt;/sup&gt;C value (&lt;em&gt;p&lt;/em&gt; &amp;lt; 0.05). Conclusion: High-frequency drip irrigation can not only reduce the amount of irrigation, and improve the utilization efficiency of irrigation water, but also put the plant in a certain state of water deficit, reduce leaf area, stomatal conductance, and transpiration rate, and then significantly reduce transpiration water consumption, improve the physiological water use efficiency of tomatoes, and realize physiological water savings.

Mulch Application and Plant Spacing Influence on Growth Traits, Pests, Insects and Weeds in Cotton (Gossypium hirsutum L.) Varieties

Mulch Application and Plant Spacing Influence on Growth Traits, Pests, Insects and Weeds in Cotton (Gossypium hirsutum L.) Varieties

Rice yield, water productivity, and nitrogen use efficiency responses to nitrogen management strategies under supplementary irrigation for rain-fed rice cultivation

Rainfall-adapted irrigation (RAI) or supplementary irrigation for rain-fed rice cultivation consumes less amount of irrigation water by harvesting rainfall and thus is vital for sustainable rice (Oryza sativa L.) production in multi-rain areas, including the Jianghan Plain in China. However, nitrogen management strategies influence rice growth and water and nitrogen utilization under RAI remains unclear. Thus, we conducted a two-year (2016 and 2017) field experiment at Jingzhou City, central China to investigate the effects of nitrogen management strategies on grain yield, crop water productivity (CWP), and nitrogen use efficiency (NUE) of rice under conventional flooding irrigation (CF) and RAI. The nitrogen management strategies included local farmers’ nitrogen fertilization (CN), common urea (30% nitrogen) blended with controlled-release nitrogen fertilizer (70% nitrogen) (U+CRF), and optimized nitrogen fertilization (ON), at a nitrogen rate of 180, 180, and 150 kg ha−1, respectively. Compared to the CF condition, RAI down-regulated the numbers of irrigation (−3 in 2016 and −4 in 2017) and reduced the total amount of irrigation water (−41.6% in 2016 and −45.6% in 2017), suggesting that rainfall-adapted irrigation enhanced the rainwater storage capacity and usage. RAI also increased root length, root and shoot biomass, net photosynthetic rate, crop growth rate, nitrogen accumulation, percentage of productive tillers, harvest index, and nitrogen harvest index. The U+CRF and ON increased or maintained these parameters compared with the CN. Compared to the traditional irrigation and nitrogen fertilization pattern (CF interacted with CN), RAI combined with U+CRF or ON enhanced root length and root biomass, and had a relatively high spikelets number per panicle, grains filled percentage, and 1000-grain weight, and thus produced a high grain yield. Moreover, the new treatment reduced amount of irrigation water and improved utilization of nitrogen fertilizer, resulting in a greater CWP and NUE. The enhanced grain yield, CWP, and NUE were associated with the increased root biomass and root length. Therefore, rainfall-adapted irrigation combined with the new nitrogen management (U+CRF or ON) can synergistically increase grain yield and resource use efficiency by improving root growth in rice.