Pre-rice Crop Research Articles

Effect of Sesbania sesban L. as a Green Manure on Yield of Rainfed-lowland Rice

Rice (Oryza sativa L.) is the most important grain crop for more than half of the world's population especially in Asia. Nitrogen (N) plays a crucial role in rice production. The incorporation of the cover crop as a pre- rice crop is the potential to improve the nitrogen used by rice crops. The experiment was conducted on the clay loam of Svay Rieng Province Cambodia in 2022 during the rice cropping season. The trial was designed using Spit-Plot design, with 4 levels of nitrogen (N) as main-plot and Cover Crop (CC) as a sub-plot. The CC was either the absence of CC or the use of incorporated Sesbania sesban L. (30 kg ha-1 ) as a pre-rice crop. The application rate of nitrogen was 0, 35, 70 and 105 kg ha–1 , respectively. Direct-seeded rice (DSR) was 100 Kg ha-1 . The size of each plot was 16 m2 (4 m×4 m). The experiment was conducted in 3 replicates. An analysis of variance (ANOVA) on Plants Height revealed a significant difference at 1% (P < 0.01) effect of nitrogen level. N35 had the greatest average height (82.95 cm) and N0 was the shortest plant height (77.15 cm). Additionally, a significant difference at 1% (P < 0.01) of planting (CC). CC1 was the tallest plant height (81.75 cm), while CC0 was the shortest plant height (78.49 cm). However, the interaction between N level and CC was not statistically significant (P > 0.05) on Plant height. An analysis of variance (ANOVA) on Grain yield showed a significant difference at 1% (P < 0.01) N70 had the highest average yield (4.92 tons/ha) and N0 had the lowest yield averaging (3.53 tons/ha). Planting (CC) was a significant difference at 1% (P < 0.01). CC1 had the highest average yield (4.60 tons/ha), while CC0 had the lowest average yield (4.13 tons/ha). the interaction between N level and CC was not statistically significant (P > 0.05) The results suggested that among 4 levels of nitrogen, The application of any rates of fertilizers increased the grain yield compared to non-N application. The grain yield was even higher with the incorporation of CC as a pre-rice crop.

Effect of Different Tillage Options and Residue Retention for Sustainable Crop Production in Wheatmungbean- Rice Cropping Pattern in Dry Areas

The study was conducted to know the productivity and soil fertility status of intensified rice-wheat (RW) systems by adding a third pre-rice crop mungbeani.ewheat-mungbeanrice cropping pattern. The trial comprises five packages of practices including crop residue retention, seeding methods with tillage options imposed on the component crops in the same cropping pattern. The results indicated that keeping standing 30% crop residue in the field with minimum disturbance of soil had significant contribution on grain yield of wheat-mungbean-rice sequence compare to conventional practice of well-till without crop residue retention. System productivity and fertility were evaluated under five levels of tillage options (zero, strip, raised bed, minimum tillage by power tiller operated system (PTOS) and conventional tillage practice (CTP) in a RWM cropping pattern. Both permanent raised bed and strip till with 30% straw retention produced the highest productivity in all years and the lowest yield was also found from conventional practice with 30% straw retention.Soil organic matter in surface soil had increased by 0.12% after 3years crop cycles with 30% SR from rice and wheat and full residue retention from mungbean crop. Straw retention is an important component of soil management and may have long term positive impacts on soil quality. The combination of raised bedsystems and strip tillage with 30% residues retained appears to be a very promising technology for sustainable intensification of wheat-mungbean-rice croppingpattern in dry zone areas.
 Bangladesh Agron. J. 2019, 22(2): 67-75

Different Tillage Options and Residue Management for Improvingcrop Productivity and Soil Fertility in Wheat-Maize-Rice Cropping Pattern

A three yearsfield experiment was conducted at Regional Wheat Research Centre, Shyampur, Rajshahiduring 2014-15 to 2017-18 with an objective to observe the effects on soil fertility and performance of the crops under different tillage and residue management for rice-wheat (RW) systems by adding a third pre-rice crop of maize. The experiment was conducted in split plot design with three replication. The tillage options viz. (i) Strip tillage (ST) (ii) Permanent bed (PB) and (iii) conventional (CT) tillage; two crop residue management, viz. (i) 0%=no residue and (ii) 30% residue retention were studied. The results indicated that keeping 30% crop residue in the field with minimum disturbance of soil had significant contribution on grain yield of wheat-maize-rice sequence compare to conventional practice of well-till without crop residue retention.The permanent bed planting system gave the highest yields of wheat (4.37 tha-1), maize (7.31 tha-1) and rice (4.40 tha-1) and followed by strip tillage and lowest in conventional tillage. Among the residue management, 30% residue retention showed the highest yields of wheat (4.46tha- 1), maize (7.39 tha-1) and rice (4.69 tha-1). Considering economic performance of all tillage systems, the permanent bed planting system performed the best among all other tillage options and followed by strip tillage. Contrarily, 30% residue retention gave the highest yield and increased 0.12-0.14% organic matter into the soil with more productive.The results indicates that, both tillage systems coupled with 30% residue retention might be a good option for higher yield as well as soil fertility for Wheat-Maize- Taman rice cropping pattern in drought prone areas of Bangladesh.
 Bangladesh Agron. J. 2019, 22(2): 55-66

Economic and environmental indicators of sustainable rice cultivation: A comparison across intensive irrigated rice cropping systems in six Asian countries

Quantifying and comparing sustainability indicators are essential to improve the sustainability of smallholder rice cropping systems. The sustainability of rice production systems can be measured based on economic, environmental, social, and institutional indicators. In this paper, we restrict our assessment to economic and environmental indicators. During 2012–2015, farmers were interviewed from 847 households from intensively irrigated rice production regions in Vietnam, Thailand, Indonesia, Myanmar, Sri Lanka, and China. We assessed the sustainability of their farming practices using economic and environmental indicators, i.e., eight of the 12 performance indicators (PIs), as defined by the Sustainable Rice Platform (SRP). Across the six sites, there was a yield gap of 24–42% and a profit gap of 36–82% between the 10% highest-performing farms (mean of top decile) and the mean-performing farms. In addition, there was a labor productivity gap of 12–32%, a nitrogen use efficiency (NUE) gap of 11–20%, a phosphorus use efficiency (PUE) gap of 1–29%, and a water productivity gap of 12–42%. Deliberate modification of conventional practices, including not flooding the field for >30 days before rice planting, incorporating pre-rice crop residue >30 days before planting, and adoption of mid-season drainage or alternate wetting and drying irrigation rather than continuous flood irrigation during the rice growing period, could substantially reduce the greenhouse gas (GHG) emission in irrigated rice fields without yield penalty. There is an urgent need to adopt improved management strategies for nitrogen (N), phosphorus (P), potassium (K) fertilizer, irrigation water-use efficiency, as well as for decreasing pesticide use frequency, without sacrificing profitability and yield. We identified the following priority interventions for each site: a) increasing fertilizer use and adopting higher-yielding varieties in Bago, Myanmar; b) reducing pesticide application rates in Can Tho, Vietnam; c) reducing fertilizer use in Guangdong, China; d) reducing nitrogen and labor use in Yogyakarta, Indonesia; e) reducing fertilizer and water use in Polonnaruwa, Sri Lanka and; f) reducing fertilizer use in Nakhon Sawan, Thailand. Additional uses of the PI analysis clearly demonstrated that rice yield and profit gaps can sustainably be closed by increasing efficiencies that will also lead to reduced environmental footprint.

Mixing groundnut residues and rice straw to improve rice yield and N use efficiency

Groundnut as a pre-rice crop is usually harvested 1–2 months before rice transplanting. During this lag phase much of N in groundnut residues could be lost due to rapid N mineralization. Mixing of abundantly available rice straw with groundnut residues may be a means for reducing N and improve subsequent crop yields. The objectives of this experiment were to investigate the effect of mixing groundnut residues and rice straw in different proportions on (a) growth and yield of succeeding rice, (b) groundnut residue N use efficiency and (c) N lost ( 15N balance) from the plant–soil system and fate of residue N in soil fractions. The experiment consisted of six treatments: (i) control (no residues), (ii) NPK (at recommended rate, 38 kg N ha −1), (iii) groundnut residues 5 Mg ha −1 (120 kg N ha −1), (iv) rice straw 5 Mg ha −1 (25 kg N ha −1), (v) 1:0.5 mixed (groundnut residues 5 Mg: rice straw 2.5 Mg ha −1), and (vi) 1:1 mixed (groundnut residues 5 Mg: rice straw 5 Mg ha −1). After rice transplanting, samples of the lowland rice cultivar KDML 105 were periodically collected to determine growth and nutrient uptake. At final harvest, dry weight, nutrient contents and 15N recovery of labeled groundnut residues were evaluated. Significant effects of residue management treatments on rice growth and nutrient uptake dynamics were observed from 30 days after transplanting onwards. At final harvest, the highest grain yield and N content of rice were obtained in the 1:1 (3.7 Mg ha −1) and 1:0.5 mixed treatments followed by sole groundnut residues > rice straw > NPK > control (2.8 Mg ha −1) treatments. There was a significant relationship between mineral N content in soil before transplanting and rice yield at harvest. Mixed residue treatments had significantly ( p < 0.1) higher groundnut-derived 15N recoveries (13%) in rice than in the sole groundnut treatment (10%) but they were lower than the recovery of labeled mineral N fertilizer in the NPK treatment (29%). The highest 15N recoveries in all treatments were observed in the topsoil (0–15 cm) where over 80% of 15N was located. Systems N unaccounted for from groundnut residues (32%) were similar to fertilizer N losses (30%), but they were lowest in the 1:0.5 mixed treatment (15%). The highest δ 13C value occurred in residue treatments and 13C was positively related to N uptake while negatively related to internal N use efficiency. The result from our study demonstrated that mixing groundnut residues and rice straw could delay N release during the pre-rice lag phase leading to an improved synchrony in N demand/supply and increased growth and yield of the succeeding rice and reduced N losses from the soil–plant system.

Root Anatomical Responses to Waterlogging at Seedling Stage of Three Cordage Fiber Crops

Waterlogging tolerance of tropical cordage fiber crops is an important agricultural subject in northeast Thailand, because they are often grown in dry-wet transition period as pre-rice crops. Since root anatomical characteristics are often considered to be important traits determining waterlogging tolerance of plants, we examined root anatomy of three fiber crops that are different in waterlogging tolerance one another. Seedlings of three cordage fiber crops, Hibiscus cannabinus (kenaf, cv. KhonKaen60), Hibiscus sabdariffa (roselle, Thai kenaf, cv. NonSoong2) and Corchorus olitorius (jute, cv. KhonKaen1), were grown in tall beakers of 1000 ml vermiculite with 40% v/v (control) and 80% v/v (waterlogging) water contents. It is known that the H. cannabinus cultivar is tolerant to waterlogging while other two species (C. olitorius, H. sabdariffa) cultivars are sensitive to waterlogging from soil-grown pot experiments in northeast Thailand. Ten days after sowing, freehand cross-sections of taproot (i.e., primary root) were made with 1 cm increments from the root tip along root axis followed by staining by toluidine blue O (0.01%) for light and fluorescence microscopy. Only H. cannabinus formed aerenchyma in cortex of the taproot under waterlogging condition. The aerenchyma of waterlogged H. cannabinus first appeared at 3 cm from the root tip and developed up to the base of taproot. The formation of aerenchyma in H. cannabinus roots may contribute to the waterlogging tolerance. Casparian bands were found in both endodermis and exodermis of taproot in all the three species. However, formation of exodermal Casparian bands was not stable, and they were restricted to the basal part of taproot in H. sabdariffa and C. olitorius. Waterlogging treatment suppressed formation of Casparian bands, particularly in exodermis.

Nutrient Uptake and Apparent Balances for Rice-Wheat Sequences. II. Phosphorus

ABSTRACT Phosphorus (P) nutrition of the rice-wheat (RW) systems of the Indo-Gangetic Plain of South Asia has become important due to the alternate flooding and drying cycles of this crop rotation. Field experiments on the RW cropping sequence were conducted at three locations of Bangladesh on three soil types. Two fertilizer doses—farmers' practice (FP) and soil-test based (STB), containing recommended amounts of P, nitrogen (N), potassium (K), and other nutrients—were compared with mungbean or maize as a third crop. The objective of the experiments was to detect P deficiency, if any, in rice, wheat, mungbean, and maize, and to compare the FP and STB doses of fertilizers in rice-wheat-mungbean and rice-wheat-maize sequences under two mungbean management practices (residue removed or retained) and one maize management practice (residue removed) in terms of P nutrition of those crops and annual system-level P removal and apparent P balance in the soil. The apparent P balance was negative with the FP dose (−1 to −9 kg ha−1 for mungbean sequences at Joydebpur and Nashipur) and there was soil P accumulation under both the STB dose (9–49 kg ha−1) and zero N control (13–50 kg ha−1) across sites. The effect of maize or mungbean as the pre-rice crop on the apparent P balance of various RW sequences was not significant. Phosphorus deficiency occurred at all sites in wheat and maize, and at Ishwordi in rice, suggesting that P fertilizer recommendations need to be revised for RW systems in Bangladesh. The results also suggest that long-term monitoring for P concentration, uptake, and balance would be necessary for improving not only the productivity and sustainability of this system but also the fertilizer P-use efficiency.

Effect of intercropping grain legume and green manure for multiple use in rice

Multipurpose legumes can be grown in the summer, grain and haulms harvested (for fodder), and the ratooned regrowth used as green manure for the following rice crop. By adopting such a system, farmers get additional income from legume grains, fodder for animals, and green manure for rice. One such system involving red gram and green gram intercropped with two green manure crops was evaluated. Field experiments were conducted at TNAU, Coimbatore, during the summer (Mar-Jun) and monsoon (Jul-Oct) seasons. The soil of the experimental field was black clay, classified taxonomically as Vertic Ustochreft, with low available N, medium available P, and high available K. Prerice crops included grain legumes, such as green gram (Vigna radiata) variety CO 45 and red gram (Cajanus cajan) variety ICPH 73, and green manure crops Sesbania rostrata and S. aculeata. In the intercropped stand, grain legumes and green manure crops were raised in a 3:1 proportion. The grain legume and green manure treatments were laid out in a randomized block design and replicated thrice.

Biological N 2 fixation and residual N benefit of pre-rice leguminous crops and green manures

Rice yields in soils of low soil organic matter may benefit from preceding leguminous green manure crops. A pre-rice crop experiment, including groundnut ( Arachis hypogaea), mung-bean (Vigna radiata), Sesbania (Sesbania rostrata), and a mixture of Sesbania and multipurpose cowpea ( Vigna unguiculata) was conducted on a characteristic sandy soil of North East Thailand. The Sesbania-cowpea intercrop gave a similar total plant biomass as the Sesbania green manure alone (7 t ha −1) but with the advantage to yield an edible product. The direct economic yield of cowpea was 1.3 t ha −1 green beans and greater than that achieved with groundnut or mungbean. The Sesbania-cowpea combination also proved to enhance rice yields by 0.8 t ha −1. The benefits in rice production were similar to the Sesbania green manure alone but surpassed the yields with the other grain crops or urea fertilizer of 30–60 kg N ha −1. Sesbania dry matter production increased with increasing planting density. The resulting variation in plant quality, e.g. lignin, however, was low. Rice responses to treatments were more related to the total residue N yields than to changes in plant quality. Apart from mungbean (25%) the pre-rice leguminous crops were able to obtain a considerable (>39%) proportion of their N from N2 fixation. The green manure Sesbania however fixed a larger proportion (79–89%) of its N than the grain crops (25–62%). This led not only to high amounts of N 2 fixed by Sesbania but together with a N harvest index of zero yielded a large systems N benefit. With grain legumes this benefit was moderated by the N export in harvestable products. In the case of mungbean this may even result in effective soil N mining. Residue N use efficiency varied between 19–29% and was similar to that obtained from a single application of chemical N fertilizer (17–28%). For the farmer the Sesbania-cowpea intercrop option seems thus the most promising one not only regarding rice yield benefits but also in terms of soil fertility enhancement and generation of edible products.

Mungbean response to surface drainage when grown as a pre-rice crop on waterlog-prone ricelands

Large areas of the world's bunded rainfed lowland ricelands could be planted to a pre-rice crop if waterlogging damage during the early wet season is prevented. To build understanding necessary to develop effective field drainage practices for pre-rice crops, pot and field studies were undertaken on a Typic Tropaquept lowland rice soil in the Cagayan Valley, Philippines. The objective of the studies was to quantify effects of excessive moisture on mungbeans ( Vigna radiata (L.) Wilczek) encountering variable regimes of duration and elevation of water table height in the root zone during a shortterm waterlogging event. Small differences in level and duration of the root zone water table markedly affected plant performance. Yields were reduced by 40–100% when the water table level reached the soil surface for 6 days compared with the unstressed treatment, but were reduced by only 12–17% when the water level was 5 cm below the surface for the same time period. Regression analysis revealed a 4% reduction in yield per centimetre increase in water table level between 5 cm below to 5 cm above the soil surface during the vegetative stage, and a 6.5% reduction per centimetre during the reproductive stage. Field experiments evaluated two prospective surface drainage techniques that farmers could employ to elevate the crop above the zone of saturation during waterlogging events. Planting in furrows, and subsequently hilling up (HU) to create ridges was unsuccessful in improving plant performance (as the base of the plant was not elevated). Planting on 25 cm high ridges formed by a plow dramatically improved growth and yield of mungbean ( ≥ 360% advantage compared with the other treatments) when subjected to a range of waterlogging stress events. Standing water occurred for 5–7 days on the soil surface of HU, broadcast seeded (B), and drilled (D) treatments, but was 56 6 cbelow the base of the plants in the ridge treatment during the two flooding events. The ridging method was observed to be effective for farm-scale use in cultivating pre-rice mungbeans with either animal or tractor power.

Grain legumes and green manures as pre-rice crops in Northeast Thailand

The loss of dry matter (ash corrected), nitrogen (N) and carbon (C) from residues of several tropical legume species was monitored using litter bags in the field over a three-month period in Northeast Thailand. This work was linked to an experiment in a farmers' field where the residual benefits of the same legume species grown before flooded rice were measured. Litter bags were incorporated in the flooded rice plots at the same time as residue incorporation in the field experiment. The species studied were Sesbania rostrata, Aeschynomene afraspera and a multi-purpose cowpea variety (Vigna unguiculata cv KVC-7). In the case of S. rostrata the breakdown of fresh and oven-dried residues and of residues buried at depths of 2-3 cm and 15 cm was also compared. Although the initial N and C concentrations were similar for all the residues they exhibited differing dry matter, N and C loss patterns. With Sesbania rostrata, 80% of the N was lost from the residues after 20 days, however, there was only a 40% decline in C and weight during the same period. The rate and amount of N loss from Aeschynomene afraspera residues was much less than with S. rostrata, declining by approximately 35% during the first 40 days. There were marked differences in rates of N loss from stem and leaves of A. afraspera indicating that monitoring the decomposition of stem and leaves combined can be misleading. In multi-purpose cowpea, loss patterns of dry matter, N and C were all similar and 50-65% was lost after 40 days burial. There was little difference between breakdown of fresh and oven-dried S. rostrata residues nor were there noticeable differences between residues incorporated superficially (2-3 cm) and buried at 15 cm. Although both %N and lignin :N ratios correlated well with weight and N loss from the residues, this was only the case when leaf and stem material were analyzed separately for A. afraspera. Despite the slower rate and smaller total amount of N released from the A. afraspera residues compared with the S. rostrata residues, a similar amount and proportion (around 20 kg N ha -1 or 22-28%) of the N was recovered from both residues by a crop of rice planted at the time of residue incorporation. This suggests a considerably higher use efficiency by rice of the N released from the A. afraspera residues (approximately 40%) compared with that for S. rostrata (30%).

Grain legumes and green manures as pre-rice crops in Northeast Thailand

Two field experiments were conducted on farmers' fields in Northeast Thailand to examine the potential of several green manure and short-duration grain legume species as pre-rice green manures. The performance of species mixtures was also investigated. Experiments were conducted under rainfed conditions both with and without recommended applications of lime, P and K fertilizers. 15N-isotope methods were used to estimate N2-fixation in the legumes and N supplied by the legume residues to a following rice crop. When provided with lime, P and K fertilizer, all legumes grew well and fixed 65–85% of their N, amounting to 59–102 kg N ha-1 wihin 90 days. The short-duration groundnut and a mixed Sesbania rostrata and multi-purpose cowpea treatment produced over 4 tonnes ha-1 residue dry weight which contained 135–150 kg N ha-1. In addition groundnut yielded almost 2 tonnes ha-1 of grain, whilst the intercrop yielded 1 t ha-1 of fresh pods of MCP, only 35% less than the sole MCP which only produced 41 kg N ha-1 in its stover. Rice dry weight increases of over 50% were found after several of the legume treatments, and 15N-based estimates indicated up to 18 kg N ha-1 was directly supplied by the legume stover to the rice. Without fertilizer application residue yields of the S. rostrata + multi-purpose cowpea mixed crop were poor (580 kg ha-1) and N2-fixation contributed only 57% of the N accumulated (20 kg N ha-1 fixed). The application of P and K fertilizers was found to approximately double residue yields with the combined addition of lime more than doubling these yields again, resulting in 88% of the legume N derived from N2-fixation (84 kg N ha-1). The following rice recovered 9–17% of the added legume N and the yield response in rice reflected the differences in legume yield. Application of P,K and lime resulted in a fivefold increase in the amount of legume N recovered by rice, indicating the importance of alleviating nutrient deficiencies through fertilizer application if green manures are to be used successfully in Northeast Thailand.