Rice Production Systems Research Articles

The sustainability of fertilizer usage in the rice production system and its influencers; evidence from Erode district of Tamil Nadu, India

ABSTRACT The advent of the green revolution, besides increasing crop yields, has also substantially increased the use of synthetic fertilizers, posing adverse effects on the environment and human health. In the present study, we aimed to gain insights into the fertilizer usage patterns of paddy farmers of the Lower Bhavani Project canal region of Erode district, Tamil Nadu, through interviews, and also tried to map the individual’s source of information regarding fertilizer usage using Social Network Analysis (SNA). Results revealed that the farmers were excessively using an average of 21 kg of N, 28 kg of P2O5 and 16 kg of K2O per acre than the recommended level. By converting the excessive nitrogen usage by farmers into carbon dioxide equivalent, we found that the excess nitrogen use has resulted in around 2,552 kg of carbon dioxide emission, which would require a year by 122 trees for absorption. By mapping the individual’s source of information using SNA, we found that progressive farmers and relative farmers were the vital information sources for fertilizer usage than the agricultural officers. It is noteworthy that the awareness and adoption of biofertilizers among the surveyed farmers were very low as only 10.2% were aware of and 1.2% were adopting biofertilizers. These findings may help formulate suitable policies for rationalizing fertilizer usage by farmers to minimize fertilizer misuse, which, if left unchecked, may pose a serious concern to the environment and human health in the coming years.

Integrated Insect Pest Management Techniques for Rice

In modern agriculture, climate change, environmental degradation, and natural resource depletion constitute one of the major potential issues for sustainable crop production and environmental management. Integrated pest management (IPM) is a promising technology for the environment. Insect pests and weeds have long posed a danger to rice production systems, resulting in severe output losses. Although insect, pest, and weed control has remained the most efficient plant protection tool, environmental risks have prompted scientists to propose alternate pest management options. The understanding of sustainable conventional agriculture prompted the broad deployment of integrated pesticide management (IPM). IPM is a multimodal pesticide management method that aims to avoid negative environmental impacts. This method is critical for delivering healthy, sustainable food to the world’s rising population. Rice is a staple crop that many developing countries rely upon for national stability and economic progress. On the other hand, rice pests represent a major biotic barrier to world rice production. This review aims to provide information on major rice pests, their identification, biology, and various IPM treatments, particularly biological management strategies. To create a sustainable rice agroecosystem, continual research and training on IPM technologies will be required.

Cutting time & height improve carbon and energy use efficiency of the forage–food dual-purpose ratoon rice cropping

Forage–food dual-purpose ratoon rice cropping (FFRR) is used to balance forage demands with ratoon rice grain yields, that is whole plant (stem and sheath, panicles) cuttings in the main season are used as forage, and rice in the regeneration season is used as food. In this study, the local ratoon rice production system as the control, we were carried out the field experiment of cultivation practices (cutting time and cutting height), and investigated the system productivity, economic benefits, carbon footprints and energy use efficiency. The energy use efficiency, energy productivity and energy profitability increased with cutting time delay, and cutting height decreased. Significant differences of these index were observed among the treatments for cutting time and cutting height (p < 0.05). Carbon efficiency and carbon sustainability index was increase with cutting time delay, and there was significant difference among the treatment of cutting time in 2018 (p < 0.05), the minimum carbon footprint of FFRR was 78.6 kgCO2 t−1 averagely at the cutting time of 30 days after the flowering stage. In 2018, the maximum net income of FFRR was 30,577 CNY hm−2 at a cutting time of 30 days after the flowering stage while the stubble height was 10 cm, and dependent on the forage yield of the main crop; in 2019, the maximum net income of FFRR was 27,326 CNY hm−2 at a cutting time of 10 days after the flowering stage while the stubble height was 10 cm, and dependent on the grain yield of the ratoon crop. Therefore, the optimal cultivation practice of the FFRR (cutting at 30 days after the flowering stage and with a stubble height of 10 cm) showed higher carbon and energy use efficiency, economic benefits of the FFRR were fluctuated with the price of forage of the main crop and rice grain of the ratoon crop.

Modelling nitrogen management in hybrid rice for coastal ecosystem of West Bengal, India.

Hybrid rice requires adequate nitrogen (N) management in order to achieve good yields from its vegetative and reproductive development. With this backdrop, a field experiment was conducted at Regional Research Station (Coastal Saline Zone), Bidhan Chandra Krishi Viswavidyalaya, Kakdwip, West Bengal (India) to record growth and yield performance of hybrid rice (cv. PAN 2423) under varied N-fertilizer doses. A modelling approach was adopted for the first time in hybrid rice production system under coastal ecosystem of West Bengal (India). In the present study, the Agricultural Production Systems Simulator (APSIM) model was calibrated and validated for simulating a hybrid rice production system with different N rates. The APSIM based crop simulation model was found to capture the physiological changes of hybrid rice under varied N rates effectively. While studying the relationship between simulated and observed yield data, we observed that the equations developed by APSIM were significant with higher R2 values (≥0.812). However, APSIM caused an over-estimation for calibrate data but it was rectified for validated data. The RMSE of models for all the cases was less than respective SD values and the normalized RMSE values were ≤20%. Hence, it was proved to be a good rationalized modelling and the performance of APSIM was robust. On the contrary, APSIM underestimated the calibrated amount of N (kg ha-1) in storage organ of hybrid rice, which was later rectified in case of validated data. A strong correlation existed between the observed and APSIM-simulated amounts of N in storage organ of hybrid rice (R2 = 0.94** and 0.96** for the calibration and validation data sets, respectively), which indicates the robustness of the APSIM simulation study. Scenario analysis also suggests that the optimal N rate will increase from 160 to 200 kg N ha-1 for the greatest hybrid rice production in coming years under elevated CO2 levels in the atmosphere. The APSIM-Oryza crop model had successfully predicted the variation in aboveground biomass and grain yield of hybrid rice under different climatic conditions.

Community based extension approaches for sustainable production of rice

Rice plays very important role in food and nutritional security in the developing world. Although India is the second largest producer (113 mt) next to China with 44 mha area under rice, its average yield (~2.6 t/ha) is far below both that of China (&gt;6 t/ha) and the global average of ~4 t/ha. Hence, along with genetic enhancement and advance crop protective measures, innovative extension approaches with agro-ecological importance, geo-political, socio-economic can support to improve the rice productivity levels with climate resilience and effective natural resources management perspectives. Moreover, the agricultural extension paradigm shift from National demonstration in 1960's to Training and visit system in 1970's to pluralistic extension approaches in 1990's has enhanced the rice production from 34.5 million tonnes in 1960-1961 to 117.5 million tonnes in 2020-2021. Still there is a huge potential to transform the rice production systems of the country through adoption of bottom-up innovative extension approaches with information and communication connectivity. Approaches like social learning, community engagement and ICT support have proven effective in dissemination and adoption of improved varieties and practices of paddy cultivation.

Overexpression of Acetyl CoA Carboxylase 1 and 3 (ACCase1 and ACCase3), and CYP81A21 were related to cyhalofop resistance in a barnyardgrass accession from Arkansas

ABSTRACT Barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.] is the most difficult-to-control weed species of rice production systems worldwide. It has evolved resistance to different herbicide sites of action, including the acetyl-CoA carboxylase (ACCase)-inhibiting herbicides. Target-site mutations conferring resistance to ACCase-inhibiting herbicides are well documented; however, the role of the different ACCase genes in conferring resistance to cyhalofop-p-butyl (cyhalofop), an ACCase-inhibiting herbicide, remains poorly understood. This research assessed the contribution of gene amplification and expression of ACCase genes in a cyhalofop-resistant barnyardgrass accession. Additionally, the expression of glutathione-S-transferases (GSTs) and cytochrome P450 monooxygenases (P450s) genes as possible contributors to resistance to cyhalofop were investigated. Results demonstrated that ACCase gene amplification does not contribute to cyhalofop resistance. However, ACCase1 and ACCase3 were found to be overexpressed in the cyhalofop-resistant barnyardgrass accession. At 24 h after cyhalofop treatment, an overexpression of 2.0- and 2.8-fold was detected in ACCase1 and ACCase3, respectively. In addition, CYP81A21 (a P450 gene) was found to be 2.5-fold overexpressed compared to the susceptible accession in the same time period. These results suggest that ACCase1, ACCase3, and CYP81A21 are crucial genes in contributing cyhalofop resistance in this barnyardgrass accession.

Rice demand and production projections for 2050: Opportunities for achieving self-sufficiency in Nepal

Rice is a major food, contributing 67% of cereal consumption in Nepal. It is playing a substantial role in food and nutritional security. Rice production is not sufficient to meet domestic consumption, so its import has been increasing. This study aims to explore whether Nepal can be self-sufficient in rice production in the current context of increasing rice demand and changing climate. We assessed the degree to which Nepal can be self-sufficient in rice production by the years 2030, 2040, and 2050, evaluating 12 different scenarios of demand driven by production, population growth, income, and climate change effect. We used compound growth rate estimation for analyzing the growth of rice production and population growth over time. Auto-regressive regression model was used to analyze the relationship of rice import and demand with domestic production, income, and population. A significant (p=0.000) positive impact of income on the import of rice was estimated, whereas significantly (p=0.000) higher impact of production on demand was estimated compared to income. Based on current rice productivity growth of 1.47% and population growth of 1.3% per year over three decades, the country will not achieve self-sufficiency until 2050.The situation would be further worsened in climate change scenarios. However, integrating the population growth rate of the last decade (0.57% per annum) with two productivity growth rate scenarios (current and (ii) 5% annual increment), the country can be self-sufficient by 2040. Based on different scenarios, the estimated demand can be met by increasing current productivity by at least 27–43% by 2030 and 42–85% by 2050. The study identified major gaps and opportunities in the rice production systems of Nepal and provided evidence-based solutions to meet the future demands in the context of increasing population and income, declining land availability, and high vulnerability to climate change.

Potential and limitations of crowdsourced data for high-resolution rice mapping in Madagascar: The importance of representation

Given the projected population growth and rice consumption in Madagascar, assessing its rice production potential is important. Existing spatial representations of rice are characterized by coarse resolutions and diverge widely. Mapping rice production based on remote sensing offers a potential solution to this problem but its application in Sub-Saharan Africa is hindered by scarce ground truth data and a complex array of cropping systems. While crowdsourcing initiatives provide data that could in principle be used to overcome this hurdle, their usefulness in rice mapping is hitherto underexplored. Here, we investigate the usefulness of crowdsourced data to enhance the mapping of rice production areas in the data-poor context of Madagascar. At present, dedicated crowdsourcing initiatives only limitedly cover rice but do provide sufficient information to build a dataset of data points characterizing a No-Rice class. On the other hand, geotagged pictures from social media, which do document rice production areas, predominantly represent 'scenic' fields appealing to social media contributors, i.e. irrigated, intensive rice production systems. The archetypal nature of these data leads to distinct feature signatures. Consequently, these data could be successfully used for rice mapping in the Lake Alaotra basin, which is characterized by the type of intensive rice cropping that is well-represented by the crowdsourced data. However, it was not possible to construct an accurate map of rice production in the greater Antananarivo region or at the national scale using crowdsourced data as they do not sufficiently represent the present variety in rice production systems. The value of crowdsourced data thus depends on the representativeness of the data, which in turn depends on the application and can be improved through applying a probabilistic sampling design. Our study also highlights the need for data representation checks prior to data augmentation or classification for future applications wanting to construct credible maps using crowdsourcing within their sampling design for which we present a multi-faceted evaluation framework.

Nutrient dynamics in water and soil under conventional rice cultivation in the Vietnamese Mekong Delta.

Background The evaluation of nutrient variability plays a crucial role in accessing soil potentials and practical intervention responses in rice production systems. Synthetic fertilizer applications and cultivation practices are considered key factors affecting nutrient dynamics and availability. Here, we assessed the nutrient dynamics in surface, subsurface water and soil under local water management and conventional rice cultivation practices in the Vietnamese Mekong Delta. Methods We implemented a field experiment (200 m 2) in the 2018 wet season and the 2019 dry season in a triple rice-cropping field. Eight samples of surface water, subsurface water (30-45 cm), and topsoil (0-20 cm) were collected and analysed during the rice-growing seasons. Results The results showed that N-NH 4 +, P-PO 4 3- and total P peaks were achieved after fertilizing. Irrespective of seasons, the nutrient content in surface water was always greater than that of subsurface water ( P < 0.001), with the exception of N-NO 3 -, which was insignificant ( P > 0.05). When comparing the wet and dry seasons, nutrient concentrations exhibited minor differences ( P > 0.05). Under conventional rice cultivation, the effects of synthetic fertilizer topdressing on the total N, soil organic matter (SOM), and total P were negligible in the soil. Higher rates of N fertilizer application did not significantly increase soil N-NH 4 +, total N, yet larger P fertilizer amounts substantially enhanced soil total P ( P < 0.001). Conclusions Under conventional rice cultivation, N-NH 4 +, P-PO 4 3- and total P losses mainly occur through runoff rather than leaching. While N-NO 3 - loss is similar in surface water and subsurface water. Notably, nutrient content in soil was high; whilst SOM was seen to be low-to-medium between seasons. Future work should consider the nutrient balance and dynamic simulation in the lowland soil of the Vietnamese Mekong Delta's paddy fields.

Farmers’ knowledge and herbicide application adoption in rice production systems in Chhattisgarh Plains of India

Farmers’ knowledge and herbicide application adoption in rice production systems in Chhattisgarh Plains of India

Development of a Manually Operated Checkrow Seeder for Rice Production Systems

The study focused on the development of a manually operated checkrow seeder for rice production systems. The machine was designed and fabricated in Alaminos City, Pangasinan. It was tested using the NSIC Rc 160 variety. Laboratory testing was done where the optimized and calibrated settings were determined. Using Design expert ® 11 for optimization, it was discovered that at a metering device hole diameter of 6 mm and 60% hopper capacity, the checkrow seeder can drop an average of 3.45 seeds per hill or 3 to 4 seeds per hill with only 3.14% damaged seeds, and 13.33 % missed hills. The results were verified through confirmation runs indicating that the generated predictive equations are reliable for the machine tests. The seeder was tested by male and female operators under actual field conditions. With the male operator, the seeder had an average of 3.23 seeds per drop, 14.06 mm seeding depth, 20% skipped rows with field efficiency of 93.13 %. With the female operator, the seeder had an average of 3.28 seeds per drop, 10 mm seeding depth, 16.67 % skipped hills with 56.25% field efficiency. In conclusion, the development of a manually operated checkrow seeder for rice production systems is possible in Alaminos City, Pangasinan. The machine can improve the method of rice establishment in the area.

Respon Petani Padi Rawa Lebak Terhadap Rencana Pembentukan Komunitas Estate Padi Di Desa Sungai Dua Kecamatan Rambutan Kabupaten Banyuasin

The Rice Estate Community (KEP) is formed by small-scale farmers in an overlay in an area by adhering to the principles of synergy, consolidation, togetherness, and sustainability. KEP is built in order to increase farming efficiency, income and welfare of farmers. Through KEP modern rice production systems, mechanization, best practice applications that are precise, controlled, and sustainable (sustain) can be achieved. This study aims to 1) describe the implementation of the KEP formation plan, 2) identify farmers' responses to the formation of KEP based on 3 indicators (cognitive, affective, and conative). The method used in this research is by using survey method. Sampling method with the census. The results showed that 1) In its implementation, KEP synergizes with other institutions to support the smooth running of KEP management. KEP will initially develop a rice business. After the rice business is running well, KEP can develop other businesses not only rice but also seed production business, provision of production facilities, organic fertilizer business, Alsin workshop service business, Alsin service management business (UPJA), and other side businesses. 2) Farmers' response to the KEP formation plan seen from 3 indicators, namely cognitive with an average score of 29.17 with agreed criteria, affective with an average score of 26.13 with agreed criteria, and conative with an average score of 27.10 with agreed criteria.

The potential of green manure to increase soil carbon sequestration and reduce the yield-scaled carbon footprint of rice production in southern China

Green manure (GM) has been used to support rice production in southern China for thousands of years. However, the effects of GM on soil carbon sequestration (CS) and the carbon footprint (CF) at a regional scale remain unclear. Therefore, we combined the datasets from long-term multisite experiments with a meta-analysis approach to quantify the potential of GM to increase the CS and reduce the CF of paddy soils in southern China. Compared with the fallow–rice practice, the GM–rice practice increased the soil C stock at a rate of 1.62 Mg CO2-eq ha–1 yr–1 and reduced chemical N application by 40% with no loss in the rice yield. The total CF varied from 7.51 to 13.66 Mg CO2-eq ha–1 yr–1 and was dominated by CH4 emissions (60.7–81.3%). GM decreased the indirect CF by 31.4% but increased the direct CH4 emissions by 19.6%. In the low and high CH4 emission scenarios, the CH4 emission factors of GM (EFgc) were 5.58 and 21.31%, respectively. The greater soil CS offset the increase in GM-derived CF in the low CH4 scenario, but it could not offset the CF increase in the high CH4 scenario. A trade-off analysis also showed that GM can simultaneously increase the CS and reduce the total CF of the rice production system when the EFgc was less than 9.20%. The variation in EFgc was mainly regulated by the GM application rates and water management patterns. Determining the appropriate GM application rate and drainage pattern warrant further investigation to optimize the potential of the GM–rice system to increase the CS and reduce the total CF in China.

A Low-Cost Wireless Sensor for Real-Time Monitoring of Water Level in Lowland Rice Field under Alternate Wetting and Drying Irrigation

The use of wireless sensors for real-time monitoring of field water level would greatly facilitate the application of alternate wetting and drying (AWD), an irrigation water management technique proven to result to significant water savings and reduced methane emissions in lowland rice production systems. However, most of the commercially available wireless sensors are generally costly. This study developed a low-cost wireless sensor that can perform real-time monitoring of water depth and surface temperature in lowland rice fields under an AWD irrigation regime. The sensor is composed mainly of an ultrasonic depth sensor, a waterproof temperature sensor, a humidity sensor, and a Wi-Fi-enabled microcontroller enclosed in a PVC cap that can be mounted in AWD pipes. The sensor was tested under laboratory, pseudo-field conditions and actual field conditions. Results showed a relatively high degree of agreement between sensor and manual measurements of water depth under all testing conditions, with the error ranging from only 5.2% to 6.6% and RMSE of 5.0 mm to 13.5 mm. The performance of the low-cost sensor also proved to be comparable with that of the high-end sensor, exhibiting practically similar measurement accuracy and higher precision. The wireless sensor developed in this study can provide a low-cost alternative to the high-cost and high-end sensors and other commercially available counterparts for efficient irrigation water management in lowland crop production systems during water-scarce conditions induced by climate change and climate variability.

Influence of Wheat Straw Return on Yield and Grain Quality in Different Direct-Seeding Rice Production Systems

Direct-seeding methods have received growing interest from rice growers. Wheat straw return is an important measure in rice-wheat rotation system. This study aimed to investigate the influence of wheat straw return on the yield and grain quality in different direct-seeding rice production systems. A split-plot design was adopted for the on-farm trial. The main plots were treated with and without wheat straw return. Dry and wet direct-seeding rice production systems were used in the split plots. The results showed that the yield of direct-seeding rice was reduced by 4.2–7.3% due to wheat straw return, which may be related to a negative effect of wheat straw return on the tiller number (p &lt; 0.05) and biomass accumulation (p &lt; 0.05). Additionally, the content of the amylose and protein of the grain of direct-seeding rice decreased by 4.3–5.5% and 6.0–6.8%, respectively, due to wheat straw return. Furthermore, wheat straw return increased the chalkiness area and the chalkiness degree of the grain of direct-seeding rice, which may be related to the reduced protein content of the grain. However, wheat straw return improved the taste score of the cooked rice (p &lt; 0.05) and the breakdown of the rapid viscosity analyzer (RVA) parameters (p &lt; 0.05), and reduced the setback of the RVA parameters, probably related to an increase in the stickness of the cooked rice (p &lt; 0.05) caused by the reduced amylose content of the grain. When compared to a dry direct-seeding rice production system, a wet direct-seeding rice production system has advantages in the tiller number (p &lt; 0.05) and biomass accumulation, thus increasing the yield and resulting in a lower content of protein and protein components, which reduces both the chalkiness area and chalkiness degree of the grain. However, by using the wet direct-seeding method, the amylose content of the grain improved; hence, the stickness of the cooked rice (p &lt; 0.05) and the breakdown of the RVA parameters decreased, and the setback of the RVA parameters increased. The above results indicated that wheat straw return reduced the yield, nutritional quality, and appearance quality of direct-seeding rice but improved the cooking quality of the grain. Although using the wet direct-seeding method is beneficial to improving the yield, it negatively impacts the grain quality of direct-seeding rice.

Can System of Rice Intensification Boost Smallholders’ Rice Production in Rainfed, Lowland Areas of Tanzania?

Based on challenges identified and approaches proposed, the paper builds a case for boosting rice production in rain[1]fed lowland areas of Tanzania. The proposed initiative is designed as an action in the field of development cooperation. Despite its complex nature, the initiative aims at an intensification of the prevailing rice production system in rainfed areas, whereby improving the availability of suitable rice seeds and adopting elements from systems of rice intensifica[1]tion (SRI) are proposed as the main agronomic components, which shall be supported by respective research. Further elements to be considered are the management of land and water in these rainfed areas, which are seasonally used for rice production, while the rest of the year they remain fallow, as well as the economics of the production system, which at present is critical and may remain a stumbling block for intensification, also due to the threat from more competitive local production in irrigated areas and cheap imports.

Scaling Up the System of Rice Intensification in 13 West African Countries

RICOWAS, the largest SRI scaling-up project to date, will be implemented over four years in 13 West African countries, starting in January 2023. RICOWAS can be considered a follow-on project to the SRI-WAAPP project, which was implemented from 2014-2016 and reached 50,048 farmers growing rice using the SRI method at 1,088 sites on 13,944 hectares across 13 countries, with 56% and 86% SRI yield increases for irrigated and rainfed lowland systems, respectively, over conventional rice production. The objective of RICOWAS is to improve climate resilience and increase the rice system productivity of smallholder rice farmers across West Africa using a climate-resilient rice production approach. The project aims to reach at least 153,000 rice growers with indirect benefits to an estimated 1.5 million people. Given the highly diverse nature of rice systems and climate zones in West Africa, RICOWAS will apply the conceptual framework for SRI with four interactive crop production principles, i) encourage early and healthy plant establishment, ii) minimize competition among plants, iii) build up fertile soils rich with organic matter and beneficial soil biota, and iv) manage water carefully to avoid both flooding and water stress. These principles remain the same no matter where SRI is applied and provide the foundation for adaptation to local conditions. With SRI at the center, RICOWAS additionally integrates agro-ecozone specific Sustainable Land and Water Management (SLWM) practices to maximize the adaptation potential of the vulnerable rice production systems throughout West Africa, calling the new approach Climate-Resilient Rice Production (CRRP).

Socio-economic factors influencing the adoption of low carbon technologies under rice production systems in China.

Rice (Oryza sativa L.) production, such as farmers' livelihood and the soil quality, has been identified to be strong influenced by climate change in China. However, the benefits of low carbon technologies (LCTs) are still debatable in rice production for farmers, which have been identified to tackle agricultural challenges. The choice of potential LCTs relevant to the case study is based on a literature review of previous empirical studies. Thus, the objectives of the study were to (1) investigate the public perception and preferences of LCTs in rice production of China, and (2) analyze the influences of the factors on farmer's decision in adopting LCTs in rice production. There were 555 farmer surveys from eight representative rice production counties in HP province of southern China, both the Poisson estimators and multivariate probit (MVP) approach were applied in the study. Our results show that water-saving irrigation, integrated pest management techniques and planting green manure crops in winter season were the three major LCTs adapted by farmers in rice production. The intensity and probability of LCTs adoptions were influenced by the main factors including farmers' education level, climate change awareness, machinery ownership, technical support and subsidies. There is a significant correlation among the LCTs, and the adoption of the technologies is interdependent, depicting either complementarities or substitutabilities between the practices. This study suggests that policies enhance the integration of LCTs would be central to farmers' knowledge, environmental concerns, technical service and financial support in rice production systems in China.

Precise delivery of nitrogen at tillering stage enhances grain yield and nitrogen use efficiency in double rice cropping systems of South China

Nitrogen fertilizer management substantially affects the growth, productivity, and nitrogen use efficiency (NUE) of rice production systems. To assess the effects of precise application of nitrogen fertilizer at tillering stage as ‘tillering-fertilizer’ on grain yield and nitrogen use efficiency, field trials were conducted in the late season of 2019 and 2020, in addition to a radioisotope 15 N tracer experiment. The experiment was comprised of four N fertilizer treatments i.e., no fertilizer application as a control (T1), traditional surface broadcast fertilization (90 kg N/ha as basal fertilizer and 60 kg N/ha as tillering fertilizer, T2), deep placement of tillering fertilizer (surface broadcast at 90 kg N/ha as basal fertilizer and 45 kg N/ha as tillering fertilizer at 10 cm depth, T3), deep placement of tillering fertilizer (surface broadcast at 90 kg N/ha as basal fertilizer and 30 kg N/ha as tillering fertilizer at 10 cm depth, T4) and two rice cultivars i.e., Wufengyou 615 and Yuxiangyouzhan . Results showed that grain yield remained 18.8% and 12.4% higher owing to increase in productive panicles and grain filling, 42.2% and 38.9% higher nitrogen agronomic efficiency, 4.6% and 10.4% higher nitrogen recovery efficiency, and 10.2% and 7.8% higher nitrogen physiological efficiency in T3 than T2 for Wufengyou 615 and Yuxiangyouzhan , respectively. Moreover, nitrogen derived from fertilizer in T3 was increased by 8.0% and 4.4% compared to T2 for Wufengyou 615 and Yuxiangyouzhan , respectively whereas the residual rate of T3 was increased by 31.5%. In addition, the T3 treatment substantially enhanced the leaf area index and leaf chlorophyll content that led to improved photosynthesis and the activities of enzymes related to nitrogen metabolism. Overall, 45 kg N/ha as tillering fertilizer at 10 cm depth and surface broadcast at 90 kg N/ha as basal fertilizer can improve grain yield as well as nitrogen use efficiency in late season rice production system of South China. • Precise delivery of nitrogen (PDN) at tillering stage (TS) can enhance grain yield in rice. • PDN at TS can improve nitrogen use efficiency in rice. • PDN at TS can increase nitrogen residual rate in the soil and decrease nitrogen unaccounted rate.

Can the advisory system Nutrient Expert® balance productivity, profitability and sustainability for rice production systems in China?

CONTEXTTo avoid excessive chemical-fertilizer application and improve agricultural productivity in rice, a fertilizer recommendation system called Nutrient Expert® (NE) was designed. However, the ability of NE to balance yield, profitability and environmental sustainability in rice production needs to be further evaluated, as it is still difficult for farmers to assess the proper nitrogen (N) application rate. OBJECTIVEThe objective of this study was to demonstrate the advantages of the NE system in balancing yield, profitability and N loss in rice production, and recommend proper N application rates for different cropping seasons of rice. METHODSThis study describes results from field experiments conducted in five main rice cropping provinces from 2017 to 2020 in China, to investigate any advantages of NE compared with local farmers' practice (FP), and to determine the proper N application rates for different cropping seasons of rice. RESULTS AND CONCLUSIONSCompared with FP, NE had 12.1% lower N-fertilizer application, but increased rice grain yield by 4.3% and net profit by 7.4%, and decreased yield-scaled N loss by 20.7%. We showed how yield, profitability and N loss were affected by N balance (i.e., N applied to the field minus N removed from the field by the harvested crop biomass), and quantified relationships between N balance and N application rate, and between N output and input. Based on relationships between N balance and N application rate, we recommend N application rates in a range from 122 to 214 kg ha−1, depending on cropping seasons of rice. We demonstrated that NE can simultaneously improve yield, profitability and environmental sustainability. SIGNIFICANCEOur study provided quantitative support for NE-based recommendations on the N application rate for smallholders farming in different rice cropping systems, and these recommendations can serve as a reference for avoiding excessive N application rate in paddy fields in other regions with similar eco-environment.