Succeeding Rice Crop Research Articles

Potassium Supplying Capacity and Contribution of Non-Exchangeable Potassium in Wetland Rice Soils in Bangladesh

ABSTRACT Information on soil potassium (K) supplying capacity, K-depletion, and contribution of exchangeable and non-exchangeable K in wetland rice ecology is limited. Understanding of K dynamics of different soil types can be a guideline for better K-fertilizer management and sustainable soil K use to achieve sustainable rice yields. To understand this soil K-supplying capacity to rice plants, a pot study with two K levels (K0 and K100 mg K kg-1 soil) was conducted with seven successive rice crops grown up to the panicle initiation stage using 18 different soils collected from across Bangladesh. The cumulative soil K-supplying capacity (242–758 mg K kg-1 soil) varied significantly (P ≤ .001) among soils, showing a strong positive relationship (R2 = 0.78) with NH4OAc K. The potential K-supplying capacity of these soils was the highest (758 mg K kg-1 soil) in Mithapukur (AEZ 3-Tista Meander Floodplain) and the lowest (242 mg K kg-1 soil) in Barura (AEZ 19-Old Meghna Estuarine Floodplain). In K0 soils, the successive cycles of rice resulted in continuous depletion of both non-exchangeable and exchangeable K pools. The concentration of both exchangeable and non-exchangeable K was maintained and almost balanced in K100 soils compared to K0 with successive rice cropping. Non-exchangeable K contribution to K nutrition of rice plants during the seventh cropping ranged, respectively, from 83% to 93% and 26% to 55% in K0 and K100 soils. Results reveal the importance of a non-exchangeable K pool in K-supplying to plants in wetland rice production systems with different soil types.

Effect of haloxyfop on narrow-leaved weeds in blackgram and its residual effect on succeeding rice crop

Effect of haloxyfop on narrow-leaved weeds in blackgram and its residual effect on succeeding rice crop

Fertilizer-N Application and Rice Straw Incorporation Impacts on Crop Yields, Potassium Use Efficiency and Potassium Fractions in a Rice–wheat Cropping System

ABSTRACT A field experiment was conducted for 5 years with four fertilizer-N rates (viz. N0, N90, N120 and 150 kg N ha−1) to rice and wheat and two rates of rice straw (RS) incorporation (RS0 and RS10; 0 and 10 Mg ha−1) in wheat arranged in a randomized complete block design to evaluate the effects on crop yields, potassium (K) use efficiency and K transformations in a sandy loam soil under a rice–wheat system (RWS). Rice straw incorporation combined with fertilizer-N application significantly (p< 0.05) increased the rice and wheat yields by ~7.2 and 3.1% as compared to no-RS (RS0), respectively. These results showed that the amount of K required to produce 1 Mg of grain yield estimated as RIUEK varied between 25.6 and 32.6 kg (Mg grain yield)−1 for rice and 20.3 and 25.1 kg (Mg grain yield)–1 for wheat. The combined RS incorporation and fertilizer-N application (N120RS10) significantly decreased the RIUEK by ~14.7 and 12.9% for rice and wheat, respectively, compared with fertilizer-N application alone. The increased crop yield, K uptake and K use efficiency (PFPK and RIUEK) were significantly related to K enrichment in water soluble-K (WS-K), exchangeable-K (Ex-K) and nonexchangeable-K (Non Ex-K), 1 N hydrochloric acid extractable-K (HCl-K), lattice-K and total K fractions by ~4.1, 2.5, 6.7, 1.4, 1.6 and 1.6 times, respectively, due to fertilizer-N application and RS incorporation, compared with fertilizer-N application alone. Rice straw incorporation before wheat establishment exerted a greater impact in terms of enhanced crops’ yield and K use efficiency of succeeding rice crop grown in an annual RWS.

↵Reducing Chemical Fertilizer use to Rice through Integrated Nutrient Management in Rice (Oryza sativa) Groundnut (Arachis hypogaea) Cropping Systems

Background: Chemical fertilizer is very expensive for most smallholder farmers in northeastern Thailand. Grain legumes can be grown in dry season to provide cash income and residues for green manure for succeeding crop. The current study was to evaluate the effect of groundnut stover incorporation to the soil integrated with chemical fertilizer on growth and yield of succeeding rice crop grown under rainfed conditions. Methods: Groundnut planted in dry season by supplemental irrigation. At harvest time, groundnut stover were sampled to determine the dry weight and analysis for nutrients content, as well as calculated the amount of nutrients return to the soil. Incorporation of groundnut stover combined 50% dose of chemical fertilizer was compared with 100% dose of chemical fertilizer treatment using by the farmer at two locations. Growth and yield of succeeding rice crop were evaluated at harvest. Result: Incorporation of groundnut stover combined 50% dose of chemical fertilizer had similar grain yields of rice to that of using 100% dose of chemical fertilizer alone as use by the farmers. This indicates that groundnut grown in dry season provided not only cash income, but also for green manure to the succeeding rice crop.

Study on Residue Management Options in Combine Harvested Rice Field in Relation to Yield and Economic Benefits of Succeeding Rice Crop

Background: Paddy straw is a good source of plant nutrients. In-situ incorporation of paddy straw affects the growth and development of succeeding rice crop by immobilization of soil available nutrients. To overcome this, paddy straw incorporated with additives and its effect on rice growth and development was studied.Methods: A field experiment was conducted at Agricultural College and Research Institute, Killikulam during October 2014 to February 2015, to study the residue management options in combine harvested rice and its effect on yield and economic benefits of rice crop. The experiment was laid out in Randomized Block Design and replicated thrice. The treatments comprised rice residue without and with additives (25 kg additional N ha-1 as basal, bio-mineralizer (2 kg t-1 rice residue), cow dung slurry (5%). The additives applied individually, combination of two and combination of all additives. Result: Different rice residue management practices exerted significant influence on succeeding rice crop. Increased number of productive tillers (409), number of grains per panicle (162), panicle length (23.8 cm), number of filled grains per panicle (132) and spikelet filled percentage (87) was recorded by T8, where straw incorporated with application of 25 kg additional N ha-1 as basal + bio-mineralizer (2 kg t-1 of rice residue) + cow dung slurry (5%). The same treatment recorded highest grain yield of 7395 kg ha-1 and straw yield of 8440 kg ha-1 and it reflected as maximum value of ₹ 1,13,646 ha-1 , 69,079 ha-1 and 2.55 of gross return, net return and B:C ratio, respectively.

Management of rice straw with relay cropping of Chinese milk vetch improved double-rice cropping system production in southern China

Improved utilization of rice (Oryza sativa L.) straw and Chinese milk vetch (Astragalus sinicus L., vetch) has positive effects on rice production. So far, few studies have investigated the productivity of vetch under different residue management practices in double-rice cropping system. The effects of rice straw on the growth and nutrient accumulation of vetch across seven years (2011–2017) and the subsequent effects of rice straw and vetch on two succeeding rice crops in a vetch–rice–rice cropping system, with the vetch established by relay cropping, were examined. The seven-year double-rice experiment consisted of the following treatments: (1) 100% chemical fertilizer (F-F100); (2) only vetch without chemical fertilizer (M-Con); (3) 80% chemical fertilizer plus vetch plus a low-cutting height (low-retained stubble) with the removal of straw (M-F80); (4) 80% chemical fertilizer plus vetch plus a low-cutting height with the retention of straw (M-F80-LR); (5) 80% chemical fertilizer plus vetch plus a high-cutting height (high-retained stubble) with the retention of straw (M-F80-HR); and (6) no fertilizer (F-Con). The yields of the two rice crops after vetch were not affected by either the cutting height of stubble with retention of straw or by the management of straw (retention vs. removal) with low-cutting height of stubble. The yields of the two rice crops after vetch were significantly higher for M-F80-HR than for M-F80-LR, but the relative contributions of the high-cutting height and straw retention to the higher rice yield could not be determined in this study. The yield stability of the double-rice grain in M-F80-HR was also increased, as determined by a sustainable yield index. Significant increases in vetch biomass and nutrient uptake were observed in the fertilized treatments during the rice season compared with the unfertilized treatments. In M-F80-HR plots, improvements in the growing environment of the vetch by conserving soil water content were associated with the highest vetch biomass, nutrient uptake, and yield stability of vetch biomass. These increased nutrient inputs partially replaced the demand for chemical fertilizer and stimulated the rice yields. It can be concluded that retaining higher-cutting stubble residues with straw retention could be the best straw management practice for increasing the vetch biomass and nutrient use efficiency, thereby allowing utilization of high-cutting height with retention of straw and vetch to improve the stability of rice productivity in a double-rice cropping system.

Study on Rice Residue Management Options on Growth Parameters and Growth Indices of Rice Crop

The research was conducted to study the effect of management options for combine harvested rice residue and its effect on succeeding rice crop growth responses. The experiment was laid out in field using a randomized block design with nine treatments and replicated three times. The computed biometric data were subjected to statistical scrutiny. Incorporation of combine harvested rice residue with 25 kg additional N ha-1 as basal + bio-mineralizer (2 kg t-1 of rice residue) and cow dung slurry (5%) recorded higher plant height, number of tillers, dry matter production (DMP), leaf area index (LAI), crop growth rate (CGR) and relative growth rate (RGR) of the succeeding rice irrespective of the growth stages. It was closely followed by straw incorporation with 25 kg additional N ha-1 as basal + cow dung slurry (5%). Incorporation of straw alone and removal of straw negatively influenced the rice growth and growth indices. Hence, it is advisable to incorporation of rice residue with additives for better growth and growth indices of rice crop.

Residual Effect of Fodders on the Succeeding Rice Crop

Residual Effect of Fodders on the Succeeding Rice Crop

Leguminous Cover Crop Astragalus sinicus Enhances Grain Yields and Nitrogen Use Efficiency through Increased Tillering in an Intensive Double-Cropping Rice System in Southern China

Chinese milk vetch (Astragalus sinicus L., vetch), a leguminous winter cover crop, has been widely adopted by farmers in southern China to boost yield of the succeeding rice crop. However, the effects of vetch on rice grain yield and nitrogen (N) use efficiency have not yet been well studied in the intensive double-cropped rice cropping systems. To fill this gap, we conducted a three-year field experiment to evaluate the impacts of the vetch crop on yields and N use efficiency in the subsequent early and late rice seasons. With moderate N input (100 kg N ha−1 for each rice crop), vetch cover significantly increased grain yields by 7.3–13.4% for early rice, by 8.2–10.4% for late rice, and by 8.6–11.5% for total annual rice production when compared with winter fallow. When rice crops received an N input of 200 kg N ha−1, vetch cover increased grain yields by 5.9–18.4% for early rice, by 3.8–10.1% for late rice, and by 6.2–11.3% for annual rice production. Moreover, comparable grain yields (11.9 vs. 12.0 Mg ha−1 for annual rice production) were observed between vetch cover with moderate N and fallow with added N fertilizer. Yield components analysis indicated that the increased tillering number was the main factor for the enhanced grain yields by vetch cover. Vetch cover with moderate and higher N input resulted in higher agronomic N use efficiency and applied N recovery efficiency compared with the fallow treatments. Here, our results showed that vetch as a winter cover crop can be combined with reduced N fertilizer input while maintaining high grain yields, thus gaining a more sustainable rice production system.

Rice yield and relationships to soil properties for production using overhead sprinkler irrigation without soil submergence

Production of irrigated rice (Oryza sativa L.) without conventional soil submergence may increase water use efficiency but risk a decline in rice yield. Spatial variability in rice yield and relationships among yield and soil properties were examined across a 3.3-ha experimental site after uniform crop management. The site was initially consolidated from small, previously puddled parcels of land into eight laser-leveled plots across a 2.1-m elevation gradient in the Philippines. Six crops of rice in rotation with three crops of mungbean (Vigna radiata (L.) R. Wilczek) were then grown from January 2012 to March 2015. The four rice crops in the dry season (crops 1, 2, 4, and 6) were irrigated using an overhead sprinkler system to maintain soil water potential greater than −10 kPa without soil submergence. Soil was puddled and flooded with irrigation for only rice crop 5 grown in the wet season. Mean rice yield with full fertilization was 6.1 Mg ha−1 for crop 2 but only 3.6 Mg ha−1 for crop 6. Yield for rice crop 6 ranged from 1.6 to 5.4 Mg ha−1 across 36 locations in the 3.3-ha site. Rice yield for crop 6 was inversely related to soil bulk density (r = −0.72 and −0.80, P < 0.001), log10 saturated hydraulic conductivity (Ksat) (r = −0.71, P < 0.001), and sand content (r = −0.63, P < 0.001). Yield was directly related to water-filled pore space of soil (r = 0.61, P < 0.001). Field locations with large downward water movement and the correspondingly most aerobic soil conditions were most prone to low rice yields and large yield decline. Rice yield was directly related to anaerobic N mineralization (r = 0.72, P < 0.001) and soil ammonium-N (r = 0.54, P < 0.001) at 16 days after transplanting and to indigenous N supply (r = 0.83, P < 0.001), as determined from rice yield without application of fertilizer N. These relationships suggested lower net N mineralization at locations with the most aerobic soil conditions, as determined by water-filled pore space. Rice yield was, however, not limited by insufficient fertilizer N. Anaerobic N mineralization and indigenous N supply were unrelated to optimum fertilizer N rate calculated from yield gain with fertilizer N, which was determined at 36 locations using paired plots with and without added N. The long rainy season and clayey soil at the site limited triple-cropping systems to two rice crops and only one non-rice crop per year. In such environments where crop rotation is not an option to prevent yield decline for rice grown without soil submergence, periodic soil submergence to increase anaerobic soil conditions would be required to sustain rice yield. Our study suggested that soil bulk density and Ksat, which can increase for successive rice crops grown without puddling and soil submergence, could serve as indicators of field locations prone to yield decline from factors other than water-deficit stress and requiring a period of soil submergence to sustain large rice yields.

Efficacy of Metamifop against grassy weeds in direct-sown rice (Oryza sativa) and its impact on succeeding crop

Metamifop is an aryloxyphenoxypropionate herbicide that controls grassy weeds. Insufficient information is available on the dose of application of metamifop for post-emergence weed control. A field experiment was conducted during 2014-15 and 2015-16 at ICAR-National Rice Research Institute to determine the most effective dose of metamifop in direct-sown rice (Oryza sativa L.) and its impact in rice-rice cropping sequence. The treatments consisted of 4 doses of metamifop 10% EC at 75, 100, 150 and 200 g/ha along with oxyfluorfen 23.5% EC at 240 g/ha as standard check. Application of metamifop at 200 g/ha effectively controlled all the grassy weeds (weed control efficiency, 80-84%) except Leptochloa chinensis. Similar trend was observed with metamifop at 150 g/ha (weed control efficiency, 76-82%). Metamifop at 150 g/ha recorded 4.59 tonnes/ha grain yield and it was at par with metamifop applied at 200 g/ha (4.84 tonnes/ha). There was no negative effect of the herbicide treatments on the germination percentage, growth and yield of the succeeding rice crop in rice-rice cropping sequence. Therefore, metamifop 10% EC at 150 g/ha would be optimum recommendation for the control of grassy weeds in rice crop, considering the lower dose for reducing the herbicide load in the environment.

Ready mix of pinoxaden and clodinafop-propargyl for control of Phalaris minor in wheat and its residual effects on succeeding rice crop

Ready mix of pinoxaden and clodinafop-propargyl for control of <i>Phalaris minor</i> in wheat and its residual effects on succeeding rice crop

Cropping system intensification: vegetable pea can replace fallow between rainfed monsoon rice and irrigated spring rice

SUMMARYThe Eastern Gangetic Plain is among the world's most intensively farmed regions, where rainfed and irrigated agriculture coexist. While the region and especially Bangladesh is a major producer of rice (Oryza sativaL. ssp.indica), there is potential to further develop sustainable rice production systems. Specifically, there is scope to include a replacement crop for the short fallow between rice crops in the dominant cropping pattern of rainfed monsoon rice harvest followed by irrigated spring rice. The aim of the current research was to identify a suitable cool-season legume crop – pea (Pisum sativumL.) or lentil (Lens culinarisMedik. ssp.culinaris) – that could be grown in the brief period between rice crops. The study comprised four crop sequence experiments comparing legume cultivars differing in maturity grown in between both long and short duration rice cultivars. These experiments were done at the Bangladesh Rice Research Institute regional station at Rajshahi over three cropping cycles. This was followed by an evaluation of pea vs. fallow between rice crops on three farmers’ fields in one cropping cycle. Here it is demonstrated that green pod vegetable pea is one of the best options to intensify the rainfed monsoon rice–fallow–spring irrigated rice cropping system, notwithstanding other remunerative rabi cropping options that could displace boro rice. The inclusion of an extra crop, pea as green pod vegetable, increased farm productivity by 1·4-fold over the dominant cropping sequence (rice–fallow–rice) and farm net income by fourfold. The study highlighted the advantages in total system productivity and monetary return of crop intensification with the inclusion of a pea crop between successive rice crops instead of a fallow period.

Sunflower allelopathy for weed control in agriculture systems

Recent developments in weed science and allied aspects have involved several interdisciplinary approaches. In this context, indiscriminate use of herbicides for weed control has become a questionable subject, which besides controlling the weeds, the chemical herbicides are harmful in many ways to soil, crops, other plants and the environment as a whole. Taking into consideration ecologically sound weed management, in modern days the reliance on chemical herbicides has decreased and a shift towards naturally occurring biological herbicides has received great attention throughout the world. Sunflower is an annual dicotyledonous plant, herbaceous, erect, and a native of North America. It is thermo and photo-insensitive, hence it can be grown year round in sub-tropical and tropical countries. Only two spp. Helianthus annuus L. and Helianthus tuberosum are cultivated for food, the remaining spp., are ornamentals weeds and wild plants. However, H. annuus is allelopathic and inhibits the growth and development of other plants thus reducing their productivity. Sunflower is a major oil-yielding crop in India and its cultivation in northwest India started 25 to 30 years ago in areas located in the plains. In this region, rice-wheat rotation became very popular owing to its high yields; however, these crops are highly infested by weeds, thus farmers use herbicides for their control. Hence, this rotation consumes a maximum quantity of herbicides in this region, which has resulted in several problems viz., environmental pollution, human health hazards, and development of herbicide resistance in weeds. Thus, serious ecological questions about the reliance on herbicides for weed control in this rotation have been raised. One of the alternatives to overcome these problems is with the use of allelopathic strategies, including the use of weed-smothering crops for weed management and for the sustainability of agriculture. The field, pot culture, and laboratory studies have shown that inclusion of sunflower crops in rotation and intercropping considerably reduced the weed population in the current and succeeding crops. Rhizosphere soil of sunflower drastically smothered the weed germination, population, and biomass. The residual suppression effect of sunflower also persisted in the next crop up to 75 days. Thus, it is conceptualized that the inclusion of such oilseed crops before the rice crop in the rice-wheat rotation may provide satisfactory weed control in the succeeding rice crops and may minimize the use of herbicides. Likewise, the replacement of sorghum by summer sunflower oilseed crops may also help in the control of summer as well as winter weeds. More studies in this direction may provide avenues for satisfactory weed management in agro-ecosystems and may help to minimize the use of herbicides and thereby pave the way to develop sustainable agricultural practices for biodiversity conservation and enhancing biological integrity.

Direct and Residual Effect of Sulphur Fertilization on Yield, Uptake and Use Efficiency in Indian Mustard and Succeeding Rice Crop

A field experiment was conducted on Indian mustard (Brassica juncea) with five levels of sulfur (S), 0, 15, 30, 45, and 60 kg S ha−1 in sub-tropical Inceptisol of Jammu, North India. The residual effect of S on rice crop was evaluated. The seed and stover yield of mustard increased in the linear order up to 60 kg S ha−1 but significant yield increase was obtained up to 30 S kg ha−1 which was 21.4 percent higher in comparison to the yield obtained in control. The uptake of S at maturity was significantly affected with all the levels of S application. The seed S uptake increased significantly up to 30 kg S ha−1 and stover 45 kg S ha−1. The residual effect of S was convincing in enhancing the rice yield to the tune of 5.3% over control, but was statistically non-significant. The S uptake was also favourably influenced by the residual S which was evidenced through increased S use efficiency. Agronomic and physiological efficiency as well as S recovery were all greatly influenced by direct and residual effect of S. Apparent S recovery was higher at 30 kg S ha−1 in mustard (12.06%).

Integration of conservation agriculture with best management practices for improving system performance of the rice–wheat rotation in the Eastern Indo-Gangetic Plains of India

Cereal production systems in the Eastern Indo-Gangetic Plains (E-IGP) are traditional, with low yield and low farm income, and they have largely missed out on the benefits of the Green Revolution. To enhance productivity, alleviate environmental and management constraints, and enhance farmers’ income in the rice–wheat cropping system of the E-IGP, new approaches that are more productive and sustainable need to be developed. Conservation agriculture (CA) together with best management practices (BMP) used in other parts of the IGP offer potential to be extended in the E-IGP. A study was conducted during 2009–2011 with the objective of evaluating a range of approaches for enhancing the productivity and economic returns of rice-wheat-based cropping systems in the E-IGP. Four scenarios (S) involving a range of crop and resource management practices with crop rotations (including legumesθ) were compared with one another, of which Scenario 1 represented farmers practice. The lowest yields of wheat (2.78–3.07tha−1) and rice (4.38–6.52tha−1) were recorded with the current farmers’ practices (S1), consisting of intensive tillage (wet tillage or puddling in rice and dry tillage in wheat) followed by inefficient crop establishment practices (transplanting in rice and broadcasting in wheat) with complete removal of crop residues. Avoiding tillage in wheat (S2) and including mungbean increased the yields of wheat and the succeeding rice crop by 21–31% and 5–10%, respectively. The yields of wheat and rice increased further by 46–54% and by 10–24%, respectively, with the inclusion of more CA components (S3). In S4, which was designed to include higher cropping intensity and diversification (potato and maize–rice–cowpea rotation) with CA components, 144–163% higher rice equivalent system productivity was attained. Irrigation water productivity in the winter season increased by 39–48% in S2, by 72–84% in S3, and by 137–138% in S4 when compared to S1 while in the rainy season it increased by 14–18% in S2, by 46–56% in S3, and by 71–88% in S4. S4 had the highest net returns ($2855–4193ha−1), followed by S3 ($1883–3246ha−1). However, the system’s highest benefit–cost ratio was recorded with S3 due to its lower cost of crop cultivation. The results of this study showed that there is enormous untapped potential to improve overall system performance through the adoption of CA in integration with BMP in the intensive system of the E-IGP of India.

Evaluation of industrial wastes as sources of fertilizer silicon using chemical extractions and plant uptake

AbstractSix inorganic industrial‐waste materials (coal fly ash, bauxite‐processing mud, steel slag, two samples of air‐cooled blast furnace [BF] slag, and one sample of water‐cooled BF slag), along with wollastonite, were evaluated as fertilizer‐Si sources. Evaluation was carried out by analyzing total and extractable Si fractions in the materials, by incubating them at two rates with a Si‐deficient soil and measuring potentially available extractable Si and by measuring yield and Si uptake by two successive rice crops grown in the fertilized soils. Of the waste materials used, fly ash had the highest total Si content (29%) but a negligible quantity was present in extractable forms. Steel slag and bauxite‐processing mud had only 5%–7% Si content while BF slags contained 14%–18% Si. All materials, other than fly ash, increased the amount of extractable Si present in the soil. Additions of steel slag and bauxite‐processing mud caused greater increases in Si extractability than the air‐cooled BF slags while water‐cooled BF slag–treated soils contained notably high acid‐extractable Si. Because of the alkaline nature of the materials, and their reaction products, there was a positive relationship between extractable soil Si and soil pH. However, an equilibration experiment using NaSiO3 as the Si source confirmed that Si solubility in the soil decreased with increasing pH. Dry‐matter yields of rice, at the lower rate of Si addition, were increased by all treatments other than fly ash. The higher rates of steel slag and bauxite‐processing mud caused yield depressions. Total Si uptake by rice was increased by all treatments, other than fly ash, and was greater at the higher rate of Si addition. It was concluded that the BF slags are the most effective waste materials as fertilizer‐Si sources and that, in slag‐amended soils, CaCl2 and NH4 acetate are the most reliable soil‐test extractants.

Effect of nutrient management and straw mulching on crop yield, uptake and soil fertility in rapeseed (Brassica campestris)–greengram (Vigna radiata)–rice (Oryza sativa) cropping system under Gangetic plains of India

An experiment was conducted at Bidhan Chandra Krishi Viswavidyalaya, West Bengal, India during 2001–2003 to study the effect of levels of fertility and straw mulch on a rapeseed (Brassica campestris var yellow sarson)–greengram (Vigna radiata)–rice (Oryza sativa) cropping system under a rainfed upland ecosystem. The experiment was laid out in a split-plot design having 14 treatment combinations of organic and inorganic nutrients along with straw mulch in three replicates. The results revealed that conjunctive use of organic and inorganic nutrients as well as paddy straw mulch resulted higher yield in both rapeseed and greengram, and the residual effects of different levels of fertilization and mulching also gave rise to higher grain yield in the succeeding rice crop. The uptake of nutrients, by the cropping system as a whole, to the tune of 204.29 and 183.00 kg ha−1 of N, 72.84 and 74.07 kg ha−1 of P and 179.95 and 175.41 kg ha−1 of K took place, with the treatment receiving 10 t ha−1 of farmyard manure (FYM) applied (to rapeseed) along with 50% recommended dose (RD) of NPK to all the crops in the sequence in two consecutive years, respectively. The same treatment resulted in a higher percentage of porosity vis-à-vis lower bulk density. Soil physico-chemical properties were superior in mulch-treated plots compared with no mulch treatment. Application of organic and inorganic nutrients along with proper moisture conservation practices can enhance the yields maintaining a good soil health.

Crop establishment, tillage and weed management techniques on weed dynamics and productivity of rice (Oryza sativa)-chickpea (Cicer arietinum) cropping system

A field study was conducted to study the effect of methods of rice establishment, tillage and weed management techniques in rice–chickpea cropping system. Treatments included four crop establishment techniques (transplanting, puddling and broadcasting sprouted rice seeds, i.e wet-seeding and dry seeding under conventional and zero tillage systems) in rice and two tillage (zero and conventional) and two weed control methods (weedy check and pendimethalin 1.0 kg/ha as pre-emergence + one hand weeding at 30 days after sowing) in succeeding chickpea. Rice field was infested with jungle rice [Echinochloa colona (L.) Link], Caesulia (Caesulia axillaris Roxb.), sessile joyweed [Alternanthera sessilis (L.) DC.], and rice flat sedge (Cyperus iria L.) and chickpea with wild oats (Avena ludoviciana Dur.) and toothed burclover (Medicago hispida Gaertn.). Results revealed that methods of rice establishment did influence the weed dynamics in rice– chickpea system. Mean yield of zero-till direct-seeded rice (3 262 kg/ha) was as good as that of puddle broadcast rice (3 343 kg/ha) and better than the transplanted rice (3 038 kg/ha). Effective weed control in preceding chickpea benefitted the succeeding rice crop. Methods of rice establishment and tillage did not influence the chickpea yield. Infestation of weeds caused 78.45% reduction in yield of chickpea. Maximum seed yield of chickpea (2 813 kg/ha) was noticed in pendimethalin followed by one HW under conventional tillage. Zero till direct-seeded rice followed by zero-till chickpea system was the best combination for maximizing system productivity, profitability and energy efficiency

Plant utilization of native soil potassium reserves by successive rice crops in Entisol, Inceptisol and Alfisols

The reserves of various forms of potassium (K), the threshold values for release of intermediate K, and the quantity/intensity (Q/I) parameters were studied in an Entisol, an Inceptisol and two Alfisols of West Bengal, India. The laboratory experiments were supplemented by a pot-culture experiment in absence of K fertilizer. The purpose was to study the release pattern of K in a rice-rice-rice cropping sequence. The results indicated that the Entisol and Inceptisol contained a higher amount of easily extractable non-exchangeable K, i.e. step-K. This was related to the dominance of micaceous minerals in clay fraction. The step-K content decreased in all the soils on subjecting them to repeated cropping. The Alfisols suffered a higher percentage decline in step-K than the Entisol and Inceptisol as observed after a sequence of three crops. The threshold values for release of intermediate K, showed a decrease in the Entisol and Alfisol studied after the third crop as compared to the first one. This was related to rather low diffusion coefficient of K for its mobility in the interlayer region. The Q/I parameters were favorable for crop growth in the Entisol examined and decreased in all the soils in course of repeated cropping.