Dietary fiber potential in Iberian-American countries: food,products and residues

The reduced intake of dietary fiber (DF) has been associated with the increase in the incidence of several non-transmissible chronic diseases. Recently many researchers from Iberian-American countries have been studying DF of food and industrial residues in order to improve technological knowledge about concentrates production as well as the development and test of enriched products originated from regional food. The present study aimed to evaluate the regional DF potential based on compilation of data about this nutrient. There is great availability of regional and traditional food with considerable DF amounts as we may find in fruits, vegetables and cereals and legumes. Concentrated sources of DF obtained from different industrial residues were characterized and evaluated making possible their utilization in food enrichment. Cookies added to corn residues (16.8% DF in integral weight) in Colombia, and pasta added to lupine fiber in Chile (11.2%) are examples of tested enriched products. Products like bread with whole wheat (12%), products for especial uses as well as pills of citric DF (55%) and food for enteral diets (1-1.9%) are already available on Cuba market. The dietary fiber contents presented in this work allow us to have an idea of the potential of such nutrient in Iberian-American countries. Such potential has been proved to be considerably representative. It is worth to inform that the complete DF database is available on the CYTED X1.6/CNPq Project Web site (http://www.fcf.usp.br/cytedxi16). It provides data on 817 regional, traditional and not conventional foods, that can be searched and utilized by professional from different areas.     

Sweet lupine (Lupinus luteus, var. Aurea/Weico and Lupinus albus, var. Multolupa) proteins. I. Extraction and filtration by Sephadex

Samples of Lupinus luteus, var. Aurea/Weico and Lupinus albus var. Multolupa flours were analyzed. The flour proteins were extracted and fractionated by gel filtration, and the per cent pattern for both globulins and albumins was then determined. The dehulled seeds, previously analyzed for composition, were ground, defatted and consecutively extracted with distilled water (pH 5.0) and phosphate buffer (0.05 M, pH 8.5). The extracted protein content was measured by the Lowry simplified method. Globulins (pH 8.5 fraction) from both species were filtered through Sephadex G-100; besides, Lupinus albus globulins were filtered through Sephadex G-150, and absorbance of the collected fractions was measured at 280 nm. The dehulled seed (DS) of L. luteus and L. albus revealed a good protein content (58.2 and 41.0%, respectively). The protein extracted from L. luteus was constituted by 17% albumins and 58.4% globulins. In contrast, L. albus presented a higher albumin content (55.6%) than globulins (31.5%). The elution pattern for the Sephadex G-200 gel filtration showed for both lupine species analyzed a preponderant peak I corresponding in L. luteus to 55.0% and in L. albus to 84.1% of the total globulins content. From these results, it may be concluded that the dehulled seed protein content is 42.0% higher for the L. luteus sample than for the L. albus. The applied methodology indicated a predominant content of globulins above albumins in L. luteus, while in the case of L. albus, the albumin content was the highest.     

Phytosterols in cereal by-products

Phytosterols are hypocholesterolemic. Like corn fiber oil, the lipid extracts of certain cereal by-products may be rich sources of these health-promoting compounds. The objective of this research was to examine the phytosterol content and composition of various cereal by-products. Total lipids in rice bran, wheat bran, wheat germ, durum wheat (bran and germ mixture), oat bran, oat hull, and corn fine fiber were extracted, and the sterol profiles of the extracted lipids were analyzed by GC. Rice bran contained the most lipids (22.2%), followed by wheat germ, durum wheat, oat bran, wheat bran, and oat hull; corn fine fiber contained the least amount of lipids (1.7%). Sitosterol, campesterol, and stigmasterol were the major phytosterols in these lipid extracts, whereas brassicasterol was detected only in wheat samples. Rice bran oil contained considerable amounts of cycloartenol and 24-methylenecycloartanol, which were unique to these samples. Total sterol concentrations in extracted lipids were similar for rice bran, wheat bran, wheat germ, and durum wheat (21.3–15.1 mg/g), but they were very low in oat bran lipids and oat hull lipids (3.4 and 8.2 mg/g, respectively). Corn fine fiber lipids contained the highest amount of sterols (48.3 mg/g). Rice bran appears to be the best source of phytosterols, with the highest oil content and high concentration of sterols.     

Determination of deoxynivalenol (DON) in wheat, barley and corn and its relationship with the levels of total molds, Fusarium spp., colonization percentage and water activity

Fifty samples of cereals including 30 of wheat (10 of wheat hard red spring), 10 of wheat soft red winter and 10 of wheat durum ámber), 10 of barley and 10 of corn (5 of white corn and 5 of yellow corn) were analyzed to detect and determine by the TLC method, the quantity of deoxynivalenol levels, which is a toxic secondary metabolite produced by Fusarium species. The aw of samples and the internal and external micoflora and Fusarium spp. levels were also investigated. Results showed that the highest grade of infection (12-80%), and the highest count of total molds (3.9 Log UFC/g) were detected in wheat samples, while the highest levels of Fusarium spp. (2.3 Log UFC/g) were detected in white corn. Deoxynivalenol was found in the wheat and barley samples but not in corn. The wheat red winter soft samples showed the highest levels of deoxynivalenol (3.2 ug/g) which is over the limit levels accepted by the FDA. Correlation was not found among count of total molds, Fusarium spp., infestation grade, aw, and deoxynivalenol levels. These results suggest that it is necessary to exert measures to avoid and to control the importation of contaminated cereals with DON levels higher to those allowed.     

Yield and functional properties of air-classified protein and starch fractions from eight legume flours

Eight legumes were pin-milled and air-classified into protein (fine) and starch (coarse) fractions and their functional properties compared with those of soybean and lupine flours. The fine material which represented 22.5 to 29% of the original flours contained from 29 to 66% protein as well as a high proportion of the flour lipids and ash. The coarse material contained 51 to 68% starch and much of the crude fiber which was dense and concentrated in the starch fraction. Generally legumes which showed highly efficient starch fractionation gave lower recoveries of protein in the fine material. High values for oil absorption, oil emulsification, whippability and foam stability were characteristics of the protein fractions, while starch fractions gave high water absorptions, peak and cold viscosities. Gelation occurred in both air-classified fractions. Pea and northern bean, chickpea and lima bean flours, and airclassified fractions gave generally higher values in the functional property tests, while fababean, field pea, mung bean and lentil gave high protein fractionation in the air classification process.     

Sweet lupine (Lupinus luteus, var. Aurea/Weico and Lupinus albus, var. Multolupa) proteins. II. Separation by electrophoresis

The albumins and globulins extracted from Lupinus luteus var. Aurea/Weico and Lupinus albus var. Multolupa defatted flour samples were analyzed by polyacrilamide gel electrophoresis. The purpose was to determine the percentage distribution of pattern in the electrophoretograms and the relative mobility values of protein. The L. luteus albumins densitogram showed six fractions, two of them, No. 2 and No. 4, represented 58.1% of the total. On the other hand, the globulins densitogram revealed five fractions, numbers 1, 2 and 3 representing 90.7%. The densitogram of peak I from Sephadex G-100 globulins filtration indicated two fractions similar to those number 1 and 2 of the total globulins, showing low relative mobility values (from 0.26 to 0.39). The L. albus albumins resolved in four fractions, with No. 2 being the most prevalent (54.3%). In regard to the L. albus globulins, these showed five fractions identical in distribution with those of peak I, fraction 2 appearing as the most important (48.2%). It was found that Sephadex G-100 did not perform a good separation. As to the relative mobility values of globulins, fractions 2 and 3 were the most prominent (relative mobility of 0.35 and 0.48, respectively). It may be concluded that L. luteus albumins presented more components but with lower relative mobility values than those of L. albus. As for the globulins from both lupine flour samples, the gel separated fractions were classified in two groups of components, those of high and of low relative mobility.     

Pea–barley intercropping and short-term subsequent crop effects across European organic cropping conditions

Grain legumes are known to increase the soil mineral nitrogen (N) content, reduce the infection pressure of soil borne pathogens, and hence enhance subsequent cereals yields. Replicated field experiments were performed throughout W. Europe (Denmark, United Kingdom, France, Germany and Italy) to asses the effect of intercropping pea and barley on the N supply to subsequent wheat in organic cropping systems. Pea and barley were grown either as sole crops at the recommended plant density (P100 and B100, respectively) or in replacement (P50B50) or additive (P100B50) intercropping designs. In the replacement design the total relative plant density is kept constant, while the additive design uses the optimal sole crop density for pea supplementing with ‘extra’ barley plants. The pea and barley crops were followed by winter wheat with and without N application. Additional experiments in Denmark and the United Kingdom included subsequent spring wheat with grass-clover as catch crops. The experiment was repeated over the three cropping seasons of 2003, 2004 and 2005. Irrespective of sites and intercrop design pea–barley intercropping improved the plant resource utilization (water, light, nutrients) to grain N yield with 25–30% using the Land Equivalent ratio. In terms of absolute quantities, sole cropped pea accumulated more N in the grains as compared to the additive design followed by the replacement design and then sole cropped barley. The post harvest soil mineral N content was unaffected by the preceding crops. Under the following winter wheat, the lowest mineral N content was generally found in early spring. Variation in soil mineral N content under the winter wheat between sites and seasons indicated a greater influence of regional climatic conditions and long-term cropping history than annual preceding crop and residue quality. Just as with the soil mineral N, the subsequent crop response to preceding crop was negligible. Soil N balances showed general negative values in the 2-year period, indicating depletion of N independent of preceding crop and cropping strategy. It is recommended to develop more rotational approaches to determine subsequent crop effects in organic cropping systems, since preceding crop effects, especially when including legumes, can occur over several years of cropping.     

Dietary fiber content and nitrogen digestibility in Central American foods: Guatemala

The study herein reported presents information on the dietary fiber content of four food groups consumed in Central America. These are: cereals, grains and products; raw and processed beans; raw and processed vegetables, and starchy foods such as potatoes, cassava and plantain. Besides data on soluble and insoluble fiber, data on in vitro protein digestibility are included. The total dietary fiber content of the wheat flour products varied from 1.62 to 2.83% on a fresh basis, with the exception of whole-wheat bread, which showed a 7.57% content. The maize tortilla presented values ranging from 3.96 to 5.21% in respect to beans, and the values for cooked and raw beans fluctuated between 6.36 and 7.00%, independent of the color; however, fried beans reported values from 15.28 to 17.58%. Vegetables contained total dietary fiber values of 1.51 to 4.34, and the tubers, from 1.31 to 2.86%.     

Biological potential of sixteen legumes in china

Phenolic acids have been identified in a variety of legumes including lima bean, broad bean, common bean, pea, jack bean, goa bean, adzuki bean, hyacinth bean, chicking vetch, garbanzo bean, dral, cow bean, rice bean, mung bean and soybean. The present study was carried out with the following aims: (1) to identify and quantify the individual phenolic acid and determine the total phenolic content (TPC); (2) to assess their antioxidant activity, inhibition activities of α-glucosidase, tyrosinase, and formation of advanced glycation endproducts; and (3) to investigate correlations among the phytochemicals and biological activity. Common bean possesses the highest antioxidant activity and advanced glycation endproducts formation inhibition activity. Adzuki bean has the highest α-glucosidase inhibition activity, and mung bean has the highest tyrosinase inhibition activity. There are significant differences in phytochemical content and functional activities among the bean species investigated. Selecting beans can help treat diseases such as dermatological hyperpigmentation illness, type 2 diabetes and associated cardiovascular diseases.     

Effect of drainage in the fallow season on reduction of CH<Subscript>4</Subscript> production and emission from permanently flooded rice fields

Field and incubation experiments were conducted during 2007–2009 to study the effect of drainage in the fallow season on CH₄ production and emission from permanently flooded rice fields. It was found that drainage in the fallow season significantly affected the temporal variations of CH₄ production and emission from permanently flooded rice fields. CH₄ production and emission from permanently flooded rice fields (Treatment FF) mainly occurred during the rice season, where they were found to be much lower in the late fallow season. No CH₄ flux was detected from drained fields (Treatment DF) in the fallow season. Compared with Treatment FF, Treatment DF was delayed not only its onset of CH₄ production and emission, but also appearance of the highest peak of CH₄ production during the rice season. A significant positive relationship was observed between CH₄ production rates of paddy soil and corresponding CH₄ fluxes (P < 0.01). CH₄ production in rice roots was the highest in rate at the rice booting stage, but was obviously lower at the rice tillering, grain filling and ripening stages, and the highest value reached at the same time as the peak of CH₄ production occurred in the paddy soil. Drainage in the fallow season significantly decreased CH₄ production and emission from Treatment FF. Compared with Treatment FF, Treatment DF was about 42–61% lower in mean CH₄ production rate in the paddy soil during the rice season, and was reduced by approximately 56% in mean CH₄ production rate in rice roots. Accordingly, Treatment DF was 20.6–30.2 g CH₄ m⁻², 39–52% lower than Treatment FF in total CH₄ emission during the rice season, and 44–57% lower in annual total CH₄ emission. Rice yield in Treatment DF tended to be 4–7% lower than that in Treatment FF.     

Nitrogen dynamics following grain legumes and subsequent catch crops and the effects on succeeding cereal crops

The effects of faba bean, lupin, pea and oat crops, with and without an undersown grass-clover mixture as a nitrogen (N) catch crop, on subsequent spring wheat followed by winter triticale crops were determined by aboveground dry matter (DM) harvests, nitrate (NO₃) leaching measurements and soil N balances. A 2½-year lysimeter experiment was carried out on a temperate sandy loam soil. Crops were not fertilized in the experimental period and the natural ¹⁵N abundance technique was used to determine grain legume N₂ fixation. Faba bean total aboveground DM production was significantly higher (1,300 g m^?2) compared to lupin (950 g m^?2), pea (850 g m^?2) and oat (1,100 g m^?2) independent of the catch crop strategy. Faba bean derived more than 90% of its N from N₂ fixation, which was unusually high as compared to lupin (70–75%) and pea (50–60%). No effect of preceding crop was observed on the subsequent spring wheat or winter triticale DM production. Nitrate leaching following grain legumes was significantly reduced with catch crops compared to without catch crops during autumn and winter before sowing subsequent spring wheat. Soil N balances were calculated from monitored N leaching from the lysimeters, and measured N-accumulation from the leguminous species, as N-fixation minus N removed in grains including total N accumulation belowground according to Mayer et al. (2003a). Negative soil N balances for pea, lupin and oat indicated soil N depletion, but a positive faba bean soil N balance (11 g N m^?2) after harvest indicated that more soil mineral N may have been available for subsequent cereals. However, the plant available N may have been taken up by the grass dominated grass-clover catch crop which together with microbial N immobilization and N losses could leave limited amounts of available N for uptake by the subsequent two cereal crops.     

Influence of agronomic management of legume crops on soil accumulation with nitrate

Nitrate is known to accumulate under legume crops. The effects of legume crop, inoculation, row width, sowing rate, sowing date, and intra-cropping with wheat, on the amount and soil distribution of mineral N, residual soil water, crop biomass and crop N were studied at Wagga Wagga in south-east Australia. After removal of most of the above-ground plant material, the treatment effects on the biomass, N content, grain yield and grain N of wheat, established in the following season, were also measured. In a later experiment at Wagga, the recovery of 15N applied to the mid-row of lupin crops established at three row widths was estimated at crop maturity. At Condobolin, row width effects on the soil distribution of mineral N, biomass, N accumulation and N fixation of crop legumes and cereals, were determined. At physiological maturity, at Wagga Wagga, very little nitrate was left beneath cereals. Significantly more was left under legume crops, mostly below 30 cm of soil depth, and it was distributed differently depending on crop, inoculation, and sampling location. More nitrate was left under pea and faba than under lupin, and in response to inoculation. Mixing wheat with narrow-leaf lupin did not prevent nitrate accumulation in soil. For most of the legumes more nitrate was left in the mid-row than in the in-row; and more nitrate was left at the mid-row of lupin crops sown with wider rows. The additional nitrate left with wider rows increased the growth, N content, grain yield and protein of wheat established in the following season. 15N labelled nitrate applied mid-row was used less effectively by lupin as row width increased, in a dry season. At Condobolin, lupin established with wide rows used less soil nitrate than with narrower rows but maintained crop N by increased N fixation. In contrast, field pea maintained N demand by increasing nitrate uptake at intermediate row spacing. The study shows that the amount of nitrate accumulated in soil during legume cropping is susceptible to agronomic management, particularly crop selection, row width and inoculation; and that variation in the amount of this nitrate may carry forward to impact wheat production in the follow-on season.     

Nutritive value of lupine and its potential as human food

The chemical composition and some indices of protein quality were measured in two species of sweet lupine Lupinus albus and Lupinus luteus grown at the Experimental Station in Gorbea, Chile: both samples showed a high protein content (39.5 and 44.6%). The protein efficiency ratio (PER) was measured in the rat and found to be 0.48 and 0.71, respectively, as compared to 2.57 for casein. Supplementation with 0.3% DL-methionine increased significantly those values, thus indicating that lupine protein is deficient in said amino acid. In another experiment the effect of cooking-extrusion on lupine flour (L. albus) was investigated and the chemical composition, protein efficiency ratio, methionine supplementation and digestibility of the protein were measured. The chemical composition was not changed but PER increased from 0.50 for raw lupine to 0.76 for processed lupine (P less than 0.05). Both values increased significantly with the addition of 0.3% DL-methionine. The protein digestibility of the supplemented lupine was not affected by the cooking extrusion process (76.5 and 77.8%, respectively). Supplementation of wheat flour with 5, 10, 15 and 20% lupine flour increased the PER of wheat flour from 0.92, to 1.39 for wheat flour supplemented with 10% lupine flour, and to 1.60 for the 15% level of the supplement. These studies seem to support the conclusion that sweet lupine is an interesting protein resource for human nutrition.     

Changes in Molecular Characteristics of Cereal Carbohydrates after Processing and Digestion

Different extraction, purification and digestion methods were used to investigate the molecular properties of carbohydrates in arabinoxylan and β-glucan concentrates, dietary fiber (DF) rich breads and ileum content of bread fed pigs. The breads studied were: a low DF wheat bread (WF), whole meal rye bread (GR), rye bread with kernels (RK), wheat bread supplemented with wheat arabinoxylan concentrate (AX) and wheat bread supplemented with oat β-glucan concentrate (BG). The weight average molecular weight (M_w) of extractable carbohydrates in β-glucan concentrate decreased eight-fold after inclusion in the BG bread when exposed to in vitro digestion, while the M_w of purified extractable carbohydrates in AX bread was reduced two-fold, and remained almost unaffected until reaching the terminal ileum of pigs. Similarly, the M_w of purified extractable carbohydrates in GR and RK bread was not significantly changed in the ileum. The AX bread resulted in the highest concentration of dissolved arabinoxylan in the ileum among all the breads that caused a substantial increased in ileal AX viscosity. Nevertheless, for none of the breads, the M_w of extractable carbohydrates was related neither to the bread extract nor ileal viscosity.     

New property of vitamin A and beta-carotene on human iron absorption: effect on phytate and polyphenols as inhibitors of iron absorption

One hundred and seventy four human subjects were studied to find out the interaction of vitamin A or beta-carotene with the inhibitors of iron absorption, from a basal breakfast containing bread from either 100 g of precooked corn flour or 100 g of white wheat flour, 50 g of cheese and 10 g of margarine. Bread was labeled with either 55Fe or 59Fe. This bread was made from commercially flours fortified with iron as ferrous fumarate and vitamins. It was noticed that the percentage of iron absorption from the breakfast prepared with precooked corn flour given alone and with different concentrations of coffee was practically the same, while the iron absorption from the breakfast prepared from wheat flour decreased from 6% when the breakfast was given alone, to less than 2% when it was given with different concentrations of coffee. The only ingredient present in precooked corn flour and not in wheat flour was vitamin A. This difference encouraged the authors to perform further experiments using precooked corn and wheat flours fortified only with ferrous fumarate. These studies demonstrated that vitamin A inhibits the effect of the polyphenol and partially inhibits the effect phytate on iron absorption. HPLC and spectrophotometric studies demonstrated an interaction between vitamin A and iron. Other experiments, which included 100 volunteers, were performed to test the effect of vitamin A and beta-carotene on iron absorption from corn, wheat and rice. The presence of vitamin A increased iron absorption up to 3 times for rice, 2.4 times for wheat and 1.8 times for corn. beta-carotene increased absorption almost 3 times for the three cereals tested, showing that both compounds were capable of preventing the inhibitory effect of phytates on iron absorption. This information suggest that vitamin A and beta-carotene form a complex with iron keeping it soluble in the intestinal lumen and preventing the inhibitory effect of phytates and polyphenols on iron absorption.     

Chemical composition of food products derived from wheat and corn produced in Costa Rica

Twenty one wheat and corn based food products elaborated in Costa Rica were analyzed by chemically with the purpose of having data on local foods. The analytical methods to determine proximate composition were AOAC's. Energy was estimated by calorimetric bomb and dietary fiber (DF) by the gravimetric enzymatic method. Also food portion size was estimated and related with DF content for food classification. The values of the nutrients per food were established and compared with others reported in foreign tables commonly used in the country. Fat and energy content in cookies are higher than in salad breads and crackers. Wheat and corn based food products are classified either as low or very low DF sources (< 2.9 g FD/portion). Corn "tortilla" DF content duplicates bread's and the fiber is basically insoluble. Marked differences were founded in the nutritive composition of specific foods when compared with values reported in foreign food tables. In other foods, as corn based products, similarities in the chemical composition were common. The chemical composition of the studied local foods shows the potential of the diet to be atherogenic, an important aspect to be considered with relation to the main causes of mortality in Costa Rica population. The more compatible food composition table with our data is the Central American, followed by the Latin American one. The necessity of having data on the chemical composition of local foods has been demonstrated.     

芹菜中膳食纤维提取工艺研究

研究了酶解芹菜干粉末制备膳食纤维的生产工艺,对影响酶解的因素进行单因素实验。进而响应面实验。最终得出适宜的酶解条件为：加酶量10％（1×10^4U／g）、温度50℃、pH4．5～5．5,在此条件下获得的膳食纤维量较高。纯度分析表明,2种膳食纤维的纯度均较高,且含较多天然叶绿素。故不溶性膳食纤维（IDF）呈淡绿色,可溶性膳食纤维（SDF）呈乳白色。     

Legume,cropping intensity,and N-fertilization effects on soil attributes and processes from an eight-year-old semiarid wheat system

In the North American northern Great Plains (NGP), legumes are promising summer fallow replacement/cropping intensification options that may decrease dependence on nitrogen (N) fertilizer in small grain systems and mitigate effects of soil organic matter (SOM) losses from summer fallow. Benefits may not be realized immediately in semiarid conditions though, and longer-term effects of legumes and intensified cropping in this region are unclear, particularly in no-till systems. We compared effects of four no-till wheat (Triticum aestivum L.) cropping systems–summer fallow–wheat (F–W), continuous wheat (CW), legume green manure (pea, Pisum sativum L.)—wheat (LGM–W), and pea–wheat (P–W)—on select soil attributes in an 8-year-old rotation study, and N fertilizer effects on C and N mineralization on a duplicate soil set in a laboratory experiment. We analyzed potentially mineralizable carbon and nitrogen (PMC and PMN) and mineralization trends with a nonlinear model, microbial biomass carbon (MB-C), and wet aggregate stability (WAS). Legume-containing systems generally resulted in higher PMC, PMN, and MB-C, while intensified systems (CW and P–W) had higher WAS. Half-lives of PMC were shortest in intensified systems, and were longest in legume systems (LGM–W and P–W) for PMN. Nitrogen addition depressed C and N mineralization, particularly in CW, and generally shortened the half-life of mineralizable C. Legumes may increase long-term, no-till NGP agroecosystem resilience and sustainability by (1) increasing the available N-supply (~26–50 %) compared to wheat-only systems, thereby reducing the need for N fertilizer for subsequent crops, and (2) by potentially mitigating negative effects of SOM loss from summer fallow.     

Long-term effect of pulse crops inclusion on soil–plant nutrient dynamics in puddled rice (Oryza sativa L.)-wheat (Triticum aestivum L.) cropping system on an Inceptisol of Indo-Gangetic plain zone of India

Given inherent qualities like N-fixation, P-solublization and nutrient recycling pulses remain the most preferred option for diversification of cereal-based rotations. A long-term experiment was used to assess the effect of including pulses in rice–wheat rotation on soil–plant nutrient dynamics under inorganic and organic nutrient management. Results revealed that pulses were equally responsive to organic and inorganic nutrient management while, growth of cereals especially wheat was restricted severely under organic production system due to low nutrient input. The annual input (kg ha^?1) of N (103.6–160.8) and P (25.9–34.7) under organic treatment was almost ½ of the recommended inorganic rate, while organics supplied higher K and S. Under organic management, the apparent balance of all the nutrients was negative whereas, inorganic fertilization resulted in positive balance of N, P and Zn. Long-term inclusion of pulses in rice–wheat rotation significantly increased soil organic C and available nutrients thus, increased the nutrient uptake by cereals. Mungbean inclusion in rice–wheat rotation significantly (P ≤ 0.05) increased uptake of N (23.0 %), P (32.9 %) and K (21.1 %) by rice crop. Continuous inorganic fertilization enriched soil available N, P, Zn and B. While organic management maintained higher SOC, available K and S over inorganic treatment. Thus, the study suggested that under organic management N and P nutrition is limiting factor for cereals and needs inorganic supplementation. The study also indicates the need for including pulses in conventional rice–wheat system for optimum nutrient acquisition and long-term soil health management.     

Nitrogen fixation by pea and lentil green manures in a semi-arid agroecoregion: effect of planting and termination timing

Crop-fallow systems dominate many semi-arid agricultural regions despite fallow’s negative effects on soil and water quality. Annual legumes grown as a fallow-replacement crop, and terminated prior to maturity, can reduce these negative effects without substantially decreasing plant available water for the subsequent crop. Interest in growing legume green manures (LGMs) in synthetically-fertilized systems is increasing in the northern Great Plains of North America, partly due to the N-fixing capabilities of legumes; however, little is known about the effects of planting and termination time on N fixation amounts in the region. A 2-year field study was initiated in southwest Montana to determine the effects of planting time (spring or summer) and termination time (e.g. flower or pod) on the amount of N fixed by field pea (Pisum sativum cv. Arvika) and lentil (Lens culinaris cv. Richlea). Two methods, ¹⁵N natural abundance and N difference, were used to quantify N fixation, with wheat or in-crop weeds as reference plants. In 2009, N fixed by spring-planted lentil was higher by pod than flower (P = 0.03). Termination time did not affect the amount of N fixed by spring-planted pea, despite more biomass by pod than flower. In 2010, both spring-planted crops fixed more N by pod than flower (P < 0.01) and more N was fixed by spring-planted than summer-planted crops (P < 0.01). These results should prove useful to growers interested in selecting management practices that optimize N fixation of LGMs.