Upland Rice Crop Research Articles

Rock dust as a source of nutrients for upland rice crop

Some farmers use rock dust as a cheap and efficient alternative to supply nutrients to plants. It is known that rock dust has the potential to replace chemical fertilization in organic production or it may complement chemical fertilization in other production systems. Thereby, the aim of this research was to evaluate the response of upland rice under different doses of rock dust. The experiment was carried out at Fazenda Cachoeira, Raul Soares city, Minas Gerais (MG), Brazil with an altitude corresponding to 360 m, sandy-clay soil. It was used BRSMG Caravera cultivar. Analysis of rock dust and soil before and after fertilization were performed to check nutrients levels present in them. It was used randomized blocks as the experimental design with five replications and four doses of rock dust: 1100, 1300, 1500, 1700 kg. ha-1, with an additional treatment consisting of NPK mineral fertilization without rock dust. Yield, weight of 1000 grains and the percentage of full and empty grains did not differ between treatments. Therefore, rock dust is a promising strategy to replace chemical fertilizer in rice crops providing equivalent yield to conventional fertilization with remarkable reduction of crop costs as well as the reduction of environmental impacts caused by the excessive use of chemical fertilizers.

Response of Bacterial Community Structure in the Bulk Soil and Rice Straw Residues under Different Crop Rotation Systems

This study investigated the effect of upland crop rotation on soil bacterial community in bulk soil and rice straw residues in the alluvial soils. Soil samples and rice straw residues in two crop rotation models including triple rice and rice-upland crops were collected for incubation under anaerobic and aerobic conditions. Data were analyzed from Denaturing Gradient Gel Electrophoresis band patterns. The results showed that the composition and diversity of communities colonizing the rice straw residues differed from those inhabiting the bulk soil. The bacterial community composition and diversity were only moderately affected by rice straw residues in the bulk soil. Especially, this study indicated that the composition of the bacterial community associated with the bulk soil and rice straw residues was dynamic in two incubation conditions (aerobic or anaerobic) and the different crop rotation models. The findings of this study demonstrated that the bacterial diversity was not affected by the difference in continuous paddy rice cultivation compared to the upland crop rotation system.

Upland rice: A new high potential non-traditional cash crop for Africa

Rice is the main staple food for almost half of the world’s population and leading cereal in terms of production area and consumption. Rapid urbanization and changes in consumer preferences have led to a concomitant increase in consumption which so far exceeds any other crop in Africa. Therefore, upland rice cropping has become a common sight in Africa as farmers engage in diversification and respond to demand for the crop. Interspecific hybridization of African rice (Oryza glaberrima Steud.) and Asian rice (Oryza sativa L.) produced upland rice NERICA varieties that combine adaptability, tolerance to stresses and high production potential. Traditional African rice varieties though adapted to the continent are prone to lodging, shattering and comparatively low yielding which adversely affects production and consequently their adoption. Some of the poorest farmers are found in Africa where there is dependence on biomass cooking fuel and upland rice has greater significance. There is, therefore, need to re-evaluate the role played by the crop, identify gaps and proffer solutions that will make it productive and widely cultivated. Accordingly, this review intends to examine upland rice production patterns and strides which can be made to sustainably increase its productivity so that there is food and nutrition security. Some of the pertinent issues that need to be considered include prioritization of farmer preferences in quality and agronomic attributes to enhance adoption. Upland rice breeding programs can go beyond traditional breeding for stresses and yield but focus on genetic biofortification to use the crop as a conduit for vital nutrients. Ultimately, for sustainable rice productivity, there is need to have affordable infrastructure to lessen labor requirement particularly during production and post-harvest processing. Moreover, there is need to build institutional capacity to conduct more research and offer extension services to support production of the crop. A wider product portfolio for the crop will subsequently have a multiplier effect and enhance adoption of rice production by many farmers in Africa. The ultimate aim is to spread awareness of upland rice as an alternative cash crop that can be produced in suitable agroecologies in Africa. Key words: Crop diversification, NERICA, Oryza glaberrima, Oryza sativa, Upland rice

Long-term outcomes of the livelihoods of displaced households after hydropower dam construction: A case study in Thua Thien Hue Province, Vietnam

Abstract Millions of people have been displaced and resettled worldwide to build hydroelectric dams. Most of the previous studies show that the livelihoods of the resettled people have been getting worse, but these studies have only been evaluated over a short time frame and only selected two-time periods for assessment, including before and after displacement. Few follow-up and evaluation studies have been conducted for periods longer than 10 years. Therefore, this study conducted a study that was long-term at a resettlement site for hydropower construction in Vietnam to observe the change in livelihoods over more than 12 years of the people that were resettled. Both quantitative and qualitative methods were used in the research to determine livelihood outcomes and to explain the causes of changes in livelihood pathways after resettlement. Our findings indicate that the loss of productive land for upland rice and dry crops was the greatest challenge for displaced households. Households which were headed by women, or those that were handicapped, were more susceptible to land loss. Displaced people also lost their traditional jobs and faced food insecurity because they did not have productive land for cultivating rice and cassava crops. As a result of this significant reduction in economic and food conditions, displaced households could not maintain their culture and religion, and the coherence of Bo Hon, the study village gradually decreased. However, displaced households made a faster recovery in income generation than other communities displaced by hydropower dams in Vietnam after 12 years. They could generate more income because they live near Hue city and receive strong support from local authorities. Through this study, it has been shown that the selection and arrangement of a suitable resettlement site with good access to the job market will be a prerequisite to help displaced households to adapt and develop their livelihoods after resettlement in conditions of limited access to natural resources.

Responses of arbuscular mycorrhizal fungi to rice–upland crop rotations in an 8‐year paddy ecosystem

AbstractArbuscular mycorrhizal fungi (AMF), which can form symbiotic associations with many terrestrial plants, are critical for crop yields and agroecosystem sustainability. In this study, we assessed the influence of rice–upland crop rotations on soil AMF diversity and composition. We also explored the mechanisms of rice (Oryza sativa L.)–upland crop rotations that affect AMF using trait‐based guild methods. We found that rotations of rice with different plants differentially influenced soil AMF. Rice–wheat (Triticum aestivum L.) (RW) and rice–Chinese milk vetch (Astragalus sinicus L.) (RV) rotations significantly altered the soil AMF composition, with RW and RV significantly increasing and decreasing AMF diversity, respectively, compared with the rice–fallow treatment. In addition, RW and RV affected AMF abundance in intra‐ and extra‐radical portions in different ways. For example, both the RW and RV treatments increased AMF spore density, but decreased AMF colonization rate. Different AMF guilds showed different responses to rice–upland crop rotations. The RW treatment increased the rhizophilic guild by 4.9% and decreased the edaphophilic guild by 27.9%, whereas the RV treatment produced opposite trends. Thus, rice–upland crop rotations changed soil AMF diversity, AMF composition, and trait‐based guilds in different ways, and rice yield was mainly correlated with AMF colonization rate.

Responses of Soil Nematodes to Combined Bio-Organo-Mineral Fertilizers on Upland Rice Cropping in the Highlands of Madagascar

Responses of Soil Nematodes to Combined Bio-Organo-Mineral Fertilizers on Upland Rice Cropping in the Highlands of Madagascar

The effect of upland crop planting on field N2O emission from rice-growing seasons: A case study comparing rice-wheat and rice-rapeseed rotations

Paddy fields, especially under flooded rice-upland crop rotation modes, undergo tremendous changes in soil redox conditions. The effects of different upland crop plantations on field N2O emissions from the rice-planting period and the underlying mechanisms are scarce. In this study, two types of flooded rice-upland cropping rotation modes, namely, rice-rapeseed rotation (RR) and rice-wheat rotation (RW), were selected to investigate the effects of different upland crop plantations on field N2O emissions during the rice-growing period, in central China. To confirm the effect of upland crop plantations on soil variables and associated functional genes, conventional rice planting (RR-CP and RW-CP) with a part of the non-rice area (RR-NP and RW-NP) during the rice season was implemented. Results revealed that seasonal N2O emissions from RR-NP and RW-NP treatments were 1.83 ± 0.18 and 1.43 ± 0.25, and 1.41 ± 0.09 and 0.88 ± 0.08 kg N ha−1, respectively, during two consecutive rice-plantation seasons, which were significantly higher than those from RR-CP treatment (1.38 ± 0.16 and 0.91 ± 0.15 kg N ha−1) and RW-CP treatment (0.95 ± 0.08 and 0.50 ± 0.10 kg N ha−1). Higher N2O emissions from RR rotation than from RW rotation, regardless of rice planting, indicated that upland cultivation affected soil N2O efflux. For rice planting treatments, strong positive relationships between N2O fluxes and soil-dissolved organic carbon (DOC), ammonium (NH4+), nitrate (NO3-), and functional genes (nirS, nirK, and nosZ genes) were observed, implying that soil available C and N, and related functional genes are key regulatory factors controlling N2O emissions. Compared with the RW-CP treatment, the higher abundance of the nirK gene and lower nosZ/(nirS + nirK) ratio from the RR-CP treatment may facilitate greater N2O production, while reducing conversion of N2O to N2, resulting in increased N2O emissions. Furthermore, structural equation model (SEM) showed that field flood depth (FD), soil available C and N, and the abundance of nirS gene, together, displayed more than 70 % impact effect on N2O emission for RR-CP treatment, while, FD, soil available N, and nirS and nirK genes, together, displayed more than 60 % impact effect on N2O emission for RW-CP treatment. Our results suggest that suitable upland crop rice cultivation could be beneficial for mitigating soil N2O emissions.

Sustainable agricultural practices to improve soil quality and productivity of soybean and upland rice

Combining cover crops with multifunctional microorganisms provides significant increments in the grain productivity of soybean and upland rice crops. However, there are still few studies that aimed to evaluate the effect of this combination on the productivity of agricultural systems. The objective of this study was to determine the effect of the mix of cover crops and the co-inoculation of multifunctional rhizobacteria on the quality of the soil, yield components, and on the grain yield of soybean and upland rice. The experimental design was in random blocks with 24 treatments in a 6x2x2 factorial scheme. Treatments were the combination of 6 (5 mix of cover crops (mixture of seeds of different cover crops species) and the control (fallow), 2 (upland rice and soybeans), 2 (co-inoculated (inoculation with two microorganisms) or not (no microorganisms), with four replications. Combination of cover crops provided an increase in Ca and Mn levels in the soil, increased activity of soil quality indicator enzymes (phosphatase and arylsulfatase), higher soybean yield, and higher number of upland rice panicles. The co-inoculation with multifunctional rhizobacteria led to an increase in phosphorus levels in the soil, the number of pods per plant, the mass of 100 grains for soybean cultivation, the number of grains per panicle, and productivity of upland rice. Therefore, a mix of cover crops, combined with the co-inoculation with multifunctional rhizobacteria are sustainable agricultural practices that can contribute to the improvement of soil quality and the increase of the productivity of soybean and upland rice crops

Product Type, Rice Variety, and Agronomic Measures Determined the Efficacy of Enhanced-Efficiency Nitrogen Fertilizer on the CH4 Emission and Rice Yields in Paddy Fields: A Meta-Analysis

Enhanced-efficiency nitrogen fertilizer (EENF) is a recommend nitrogen fertilizer for rice production because of its advantage on improving nitrogen use efficiency. However, its efficacy on CH4, the dominant greenhouse gas, emission from rice fields showed great variation under field conditions. And the factors influencing its efficacy are still unclear. We synthesized the results of 46 field studies and analyzed the impact of product type, rice variety, and primary agronomic measures (rice cropping system, nitrogen (N) application rate, and water management options) on the effectiveness of EENF on the CH4 emission and rice yield. Overall, EENF, including inhibitors (IS) and slow/control-released fertilizer (S/CRF), significantly reduced CH4 emission by 16.2% and increased rice yield by 7.3%, resulting in a significant reduction in yield-scaled CH4 by 21.7%, compared with conventional N fertilizer. Nitrapyrin, DMPP (3,4-dimethylpyrazole phosphate), and HQ (Hydroquinone) + Nitrapyrin showed relative higher efficacy on the mitigation of CH4 emission than other EENF products; and HQ showed relative lower efficacy on rice yield than other EENF products. The reduction in CH4 emission response of hybrid rice varieties to IS and S/CRF was greater than that of inbred rice varieties. IS significantly reduced the CH4 emission and increased the rice yield under all three rice cropping systems, and showed the highest efficacy in the late rice season of double rice cropping system. Whereas, S/CRF did not significantly reduce the CH4 emission from rice seasons of single rice cropping system and rice-upland crops rotation system. IS did not reduce the CH4 emission when N application rate less than 100 kg ha−1, and S/CRF did not affect the CH4 emission when N application rate less than 100 kg ha−1 or above 200 kg ha−1. Continuous flooding was unfavorable for IS and S/CRF to mitigate CH4 emission and enhance rice yield. These results emphasized the necessary to link EENF products with rice varieties and agronomic practices to assess their efficacy on CH4 emissions and rice yield.

Emissions of Greenhouse Gases and NO from Rice Fields and a Peach Orchard as Affected by N Input and Land-Use Conversion

Nitrogen (N) inputs and land-use conversion are management practices that affect soil greenhouse gas (GHG) and nitric oxide (NO) emissions. Here, we measured soil methane (CH4), nitrous oxide (N2O), and NO fluxes from rice fields and a peach orchard that converted from paddies to assess the impacts of nitrogen (N) inputs and land-use conversion on their emissions. Treatments included four paddy field treatments (PN0, PN160, PN220, and PN280) and one peach orchard treatment (ON280) with number indicating the N-input rate of kg N ha−1. The results showed that cumulative emissions of CH4, N2O and NO ranged from 28.6 to 85.3 kg C ha−1, 0.5 to 4.0 kg N ha−1 and 0.2 to 0.3 kg N ha−1 during the rice-growing season, respectively. In terms of greenhouse gas intensity, the PN280 treatment is the recommended N application rate. Land-use conversion significantly reduced the global warming potential from croplands. The conversion shifted soils from an essential source of CH4 to a small net sink. In addition, N2O emissions from the rice–wheat rotation system were 1.8 times higher than from the orchard, mainly due to the difference in the N application rate. In summary, to reduce agriculture-induced GHG emissions, future research needs to focus on the effects of N inputs on rice-upland crop rotation systems.

Application of Macro and Micro Fertilizers on Upland Rice Crops Inoculation of Biofertilizers in Bengkulu Coastal Land

Coastal land located in the lowlands near the coast has a marginal Entisol soil type. Entisols have the following characteristics: loose soil aggregate, sensitive to erosion, and low levels of nutrients, organic matter, water holding capacity, and soil fertility. The nature of this Entisol is less able to produce maximum upland rice production. The technology used to overcome this problem is by applying macro and micro fertilizers to the soil, which is planted with upland rice seeds, inoculated with biological fertilizers so that it is hoped that upland rice production can be maximized. The purpose of this study was to obtain high upland rice production in coastal areas. The research was carried out from June to December 2020 in Beringin Raya Village, Muara Bangkahulu District, Bengkulu City. The research location is located at coordinates S 03?45'23'' E 102?15'41''. The experimental design used was Completely Randomized Block Design (CRBD) with 2 factors, namely types of fertilizers and varieties of upland rice. The first factor consists of P0 = No fertilizer; P1 = compound micro fertilizer; P2 = Fertilizer recommended for upland rice from the Institute for Agricultural Research and Technology). The second factor consists of V1 = red upland rice; V2 = white upland rice) The results showed that there was an interaction between the type of fertilizer and upland rice varieties on soil pH (KCl 1:2.5 w/v). the interaction of microfertilizers with white upland rice varieties resulted in the highest soil pH (5.06). The best type of fertilizer is micro-compound fertilizer which produces soil pH (KCl 1:2.5 w/v), P nutrient uptake, the highest root colonization and the highest number of production tillers and the highest grain weight per plant and upland rice yield per plot. The best upland rice variety was the white variety which produced the highest uptake of P nutrients, the number of productive tillers, the weight of grain per plant and the highest yield per plot.

Exploring the synergism between surface liming and nitrogen fertilization in no‐till system

AbstractSurface liming to correct soil acidity may have limited effectiveness in subsurface layers in no‐till systems (NTS). The possibility of downward movement may be increased when liming is combined with fertilization with urea (ammoniacal N), as NO3– formed by nitrification of NH4+ can form ion pairs with exchangeable Ca2+ and Mg2+. Liming can also increase the nitrogen use efficiency (NUE) of crops and reduce dependence on soil N. In this work, we investigated the effects of surface application of lime under NTS and N topdressing on soil chemical properties and the nutrition, productivity, and NUE of maize (Zea mays L.) and upland rice (Oryza sativa L.). The treatments comprised four lime rates applied superficially (0, 1,500, 3,000, and 6,000 kg ha–1), and absence (–N) or presence of N fertilization (+N) as urea by topdressing. The treatments were applied during two agricultural years (2011/2012 and 2012/2013), with maize in the first crop season and upland rice in the second crop season. At 18 mo after liming, the application of 6,000 kg lime ha–1 significantly improved the chemical attributes of the soil (pH, soil organic matter (SOM), K, Ca2+, Mg2+, and base saturation [BS]). The application of urea increased the mobility of Ca2+ and Mg2+ to greater depths. The combination of 3,000 kg lime ha–1 with N fertilization synergistically increased the nutrition (N, P, and S), grain yield, and N‐related efficiency indexes in the maize and upland rice crops.

Carryover Effect of Biochar and Cow Dung Manure on the Productivity of Green Gram (Vigna radiata L.) in Typic haplustalf

Background: In cereals based legume cropping system more importance and intensification are given to first crop (cereals) as compared to succeeding crops. Hence, succeeding crops yield got reduced due to grown in low fertile soils. Productivity of green gram have declined or stagnated in recent years though we grew high yield varieties, due to grown in marginal lands with low nutrient and moisture. Biochar is organic substance that highly persists in soils with very little biological decomposition and helps to store nutrients and moisture for succeeding crop. The present investigation was felt necessary to get utilize the residual soil nutrients and moisture from the preceding biochar applied upland rice field for sustainable yield of green gram crop. Methods: The present investigation was conducted during kharif season 2018. The study was conducted in randomized black design with sixteen treatments consisting of four levels of coconut shell biochar (CSB) at 2, 4, 6 and 8 t ha-1 and two levels of cow dung manure (CDM) at 5 and 10 t ha-1 with applied alone and in combinations with three replications (applied for previous upland rice crop). The recommended dose of NPK fertilizer (20:50:50 kg ha-1) for green gram was common except absolute control. Result: The study results indicated that, residual effect of previously applied biochar and cow dung manure had a significant effect on succeeding green gram crop productivity in acid sandy loam soils due to its liming effect on improving soil properties and nutrient availability. Especially, combination of coconut shell biochar (CSB at 8 t ha-1) and cow dung manure (CDM at 10 t ha-1) with recommended NPK fertilizers.

​Yields and its Component Characters in Upland Rice of Manipur

Background: Yield is a complex entity. The pre-requisite for achieving high yields in rice depends on identification of superior new genotypes for various traits associated with yield. These characters may help in advancing the yield like the plant height, tillers per plant, length of panicle, grains per panicle, grain weight and their relationship with yield and direct and indirect contribution to grain yield. The present study was conducted to identify the yield and its related characters of all the rice cultivars which are collected from the hill farmers of Manipur. Methods: Field experiment of 90 local rice cultivars were conducted in the experimental farm of ICAR, Lamphel, Imphal, Manipur. Sample random sampling technique with a sample size of 6 competitive plant were study in the present study. Data of plant height, total tillers per plant, length of panicle, total spikelet’s per panicle, grain per panicle, grain weight, grain yield per plant were analysed. Result: The present finding shows that a large number of local cultivars are used by the hill farmers of Manipur without appropriate selection. Some of these cultivars were having those agronomic traits which are considered to be associated with yield characters of rice. If improved high yielding varieties for upland rice cropping is not available to the farmers’ they can select to those local cultivars having desirable yield characters.

Field arbuscular mycorrhizal inoculation increased plant performance without phosphorus fertilizer supply of four promoted upland rice varieties in Madagascar

Summary In Madagascar, upland rice cropping is constrained by soil acidity and low phosphorus (P) bioavailability. Given their role in plant P nutrition, arbuscular mycorrhizal fungi (AMF) may improve crop yield in nutrient-poor tropical soils. In the Vakinankaratra region, a field experiment was conducted at 908 m asl on an acidic Ferralsol during the 2019–2020 growing season. The aim was to test the ability of four promoted rice varieties to respond to AMF seed-coating inoculation with a commercial strain of Rhizophagus irregularis in the absence or presence of P fertilizer (20 kg ha−1 of P2O5) under no expected nitrogen (N) limitation. In absence of P fertilization, both at tillering and at maturity and irrespective of the rice varieties, AMF inoculation significantly improved plant performance and finally grain yield, grain N, and grain P amounts by an average of 28%, 30%, and 39%, respectively. In contrast, when P fertilizer was supplied, no significant effect of AMF inoculation was observed. Rice growth variables were significantly higher with the application of P fertilizer than with AMF inoculation both at tillering and at maturity. P fertilizer without inoculation provided an average grain yield improvement of 85%. At tillering, mycorrhizal parameters for root colonization assessment were not positively linked with rice growth variables suggesting an early effect of AMF inoculation. We concluded that, with no P fertilization, AMF seed coating inoculation at the field scale significantly improved upland rice plant performance in a limited soil P environment. Our rice genetic variability did not interfere significantly both with mycorrhizal parameters and crop AMF inoculation benefits.

Aplicação a lanço de rochas silicáticas moídas como fontes de potássio para culturas de grãos

Abstract The objective of this work was to evaluate the agronomic and economic efficiency of phonolite rock (K2) and alkaline potassium-silicate rock (K3), ground and applied by surface broadcasting, as K sources for the soybean (Glycine max), corn (Zea mays), common bean (Phaseolus vulgaris), and upland rice (Oryza sativa) crops. Four experiments – one with each crop – were conducted in two crop years in a Typic Haplorthox in a randomized complete block design with four replicates. The treatments consisted of three sources (the KCl standard source, K2, and K3) and four rates (0, 0.5, 1.0, and 2.0 times the recommended for each crop) of K. The three sources increased similarly the leaf K concentration of soybean, corn, and common bean but had no effect on that of upland rice. The grain yield of all crops increased with the application of K2 and K3, as observed for KCl. The efficiency of the alternative K sources varies depending on the rate and crop. The K3 source is viable to be applied by broadcasting at the recommended K rate for all studied crops, while K2 is suitable only for soybean, corn, and common bean.

Spatial and temporal changes of paddy rice ecosystem services in China during the period 1980–2014

The ecological systems services or multi-functionality of paddy rice cultivation are critical to the functioning of the Earth's life-support system. We estimated the ecosystem services value (ESV) of paddy rice during 1980–2014 across China. The results indicated that the ESV of the paddy field in China showed an upward trend during this period. The share of ESV on CO2 sequestration was the highest, followed by ESV on temperature cooling and greenhouse gas (GHG) emission. The yield-scaled ESVs of Zones II (southern rice–upland crops rotation regions) and III (southern double rice production regions) were similar and significantly higher than the ESVs of Zones I (northeastern single rice production regions) and IV (Southwest rice–upland crops rotation regions). Between 1980 and 2014, the ESV of each region increased to varying degrees, except for the ESVs of Guangxi, Zhejiang, Fujian, and Guangdong. Such effects suggest the existence of a significant spatial–temporal variation in the total amount, structure, and density of ESV of paddy fields in China, which can further guide the development of future options for the adaptation of healthy rice production in China.

Forecasted Rainfall and Temperature: Basis for one-year Planting Calendar for Upland Rice (Oryza Sativa L.) in Bayombong, Nueva Vizcaya

The study aimed to determine a planting calendar for upland rice (Oryza Sativa L.) in Bayombong and its nearby municipalities based on temperature and rainfall data of the said localities together with the temperature and water requirements of the upland rice. Ten years of data on Temperature and Rainfall in Bayombong were used to forecast 12 months of data on temperature and rainfall using three forecasting methods of the SPSS, NCSS, and MS Excel. Upland rice crop can be grown successfully where the average temperature is 21 0C or more for the 5 to 6 months; it has 10 stages starting from the germination stage to the ripening stage; the temperature and water requirements in its stages must be maintained within what the plant required to sustain plant growth and development. The forecasted data on temperature and rainfall were then matched to the temperature and water requirements of the upland rice starting from germination to ripening which will be ready for harvesting. The study was able to determine the best timing for the plant the upland rice; it is on the third week of April up to the last week of August. Upland rice planted at this time interval has a high forecasted percentage of survival as the temperature and water requirements of the plant in its stages were all sustained.

The stratification of soil organic carbon and total nitrogen affected by parent material and cropping system

The stratification ratio (SR) is a good indicator of the quantitative evaluation of the soil nutrient variation with depth, which is inter-related with nutrient cycles and agricultural productivity. However, the effects of the parent material and cropping system on the SR of soil organic carbon (SOC) and total nitrogen (TN) have received little attention. The current study collected 444, 437, and 363 soil samples at the depths of 0–20, 20–40, and 40–60 cm, respectively, in subtropical southwest China, where the predominant parent materials are alluvial deposits, purple shales, and limestone and the cropping systems are rice–upland crop rotation, upland crop rotation, and rice monoculture. A two-way analysis of variance (two-way ANOVA) and a redundancy analysis (RDA) were applied to investigate the effects of the parent material, cropping system, topography, and climate on SOC and TN contents, and the corresponding SR (SR1, 0–20 cm:20–40 cm; SR2, 0–20 cm:40–60 cm). Results indicated that the parent material and cropping system were the main factors linked to the SR of the SOC and TN, whereas topography and climate seemed to have weaker effects on the SR in the agricultural landscape. Generally, alluvial deposit- and purple shale-derived soils presented higher SR than limestone-derived soils. Rice–upland crop rotation systems increased the SR compared to rice monoculture and upland crop rotation systems. Exceptions were observed in rice–upland crop rotation and rice monoculture systems under limestone. The study highlighted the efficient SR indicator in examining the SOC and TN depth distribution corresponding to the parent material and cropping system and is expected to provide valuable information regarding the optimization of the cropping pattern in different lithological regions, thereby enhancing agricultural productivity.

English

Background: Manganese (Mn) being one of the micronutrients available in acid soils acts crucial role in crop plants. In Assam soil, its concentration is 3-52 ppm whereas in plants the critical limit is 2-3ppm. Although the effects Mn on plants have been well documented, information on its impacts on yield and yield components in upland rice crop grown in Assam was scanty, and deserved its investigation. Method: A pot experiment was carried out to study the effects of Mn (0, 10,20,30 ppm Mn as MnSO4H2O) foliar spray (each 1000cm3) at vegetative stage i.e.70days after sowing, on yield and yield components of ten rice genotypes (Kanaklata, Mulagabharu, Kapilee, Disang, Kolong, Joymoti, Jyoti Prasad, Luit, Lachit and Chilarai) cultivated in Assam. Conclusion: The lower dose of Mn (10ppm) significantly increased panicle length (16.29-37.46%), panicle weight (10.54-19.50%), panicle number per plant (4.54-13.63%), number of seeds per panicle (18.38-36.48%), test weight (7.21-29.15%), high density grains (5.59-30.45%), economic yield (14.40-28.03%), biological yield (32.58-47.70%), and harvest index (3.2-7.90%). 30ppm Mn affected adversely all the physiological attributes in the study. Among the ten genotypes, Kanaklata performed the best followed by Chilarai in the experiment.