Grain mineral concentrations and yield of wheat grown under organic and conventional management

On the low‐P soils in southeastern Australia, organic crops differ from conventional ones primarily in the use of relatively insoluble, as opposed to soluble, P fertilisers and in the non‐use of herbicides. As organic management, particularly elimination of soluble fertilisers, is often claimed to enhance grain mineral concentrations, we examined grain from wheat on paired organic and conventional farms in two sets of experiments: (1) four pairs of commercial crops (1991–1993); and (2) fertiliser experiments on one farm pair where nil fertiliser was compared with 40 kg ha^?1 of P as either relatively insoluble reactive phosphate rock or more soluble superphosphate (1991 and 1992). All wheat was grown following a 2–6 year legume‐based pasture phase. Both conventional management and the superphosphate treatment greatly increased yields but reduced colonisation by mycorrhizal fungi. While only minor variations occurred in grain N, K, Mg, Ca, S and Fe concentrations, conventional grain had lower Zn and Cu but higher Mn and P than organic grain. These differences were ascribed to: soluble P fertilisers increasing P uptake but reducing mycorrhizal colonisation and thereby reducing Zn uptake and enhancing Mn uptake; dilution of Cu in heavier crops; and past lime applications on the organic farm decreasing Mn availability. These variations in grain minerals had nutritional implications primarily favouring the organic grain; however, organic management and, specifically, elimination of soluble fertilisers did not induce dramatic increases in grain mineral concentrations. In addition, organic management was coupled with yield reductions of 17–84 per cent due to P limitation and weeds. The impact of large regional variations in the characteristics of organic and conventional systems on the general applicability of the results from this study and other similar studies is discussed. Copyright © 2004 Society of Chemical Industry     

Effect of phosphate source,rate and cadmium content and use of Penicillium bilaii on phosphorus,zinc and cadmium concentration in durum wheat grain

Field studies were conducted over 3 years at several locations in Alberta and Manitoba, Canada to evaluate the impact of phosphate fertiliser containing varying concentrations of Cd on grain yield and P, Zn and Cd concentration in durum wheat grain. The effect of a seed treatment with Penicillium bilaii, a phosphate‐solubilising fungus, was also examined. P bilaii had little effect on crop yield, nutrient concentration or the concentration of Cd in the grain under the conditions of this study. Fertilisation with monoammonium phosphate consistently increased Cd concentration and Cd/Zn ratio and decreased Zn concentration in durum wheat. Increases in Cd concentration in durum wheat were unrelated to Cd concentration in the fertiliser, although the concentration of Cd in the fertiliser sources varied from 0.2 to 186.0 µg g^?1. Increased Cd concentration with phosphate application may be related to high ionic strength, reduced pH and enhanced root proliferation in the microregion around the fertiliser granules. Enhanced root development in response to phosphate fertilisation may increase the accumulation of Cd. Reduction in Zn accumulation associated with phosphate application may also contribute to the increase in Cd concentration in durum grain, possibly through enhancement of Cd translocation to the grain. While reduction in Cd concentration in phosphate fertilisers will reduce long‐term Cd accumulation in soils, use of low‐Cd fertiliser at commercially practical levels of fertilisation is unlikely to reduce Cd concentration in durum wheat in the year of application. © 2002 Society of Chemical Industry     

Impacts of phosphorus and zinc levels on phosphorus and zinc nutrition and phytic acid concentration in wheat (Triticum aestivum L.)

BACKGROUND: Zinc (Zn) and phytic acid content in grain crops are directly related to their nutritional quality and therefore human health. To investigate the nutritional influences of phosphorus (P) and Zn levels on wheat (Triticum aestivum L.), plants were grown hydroponically to maturity in chelator‐buffered solutions. RESULTS: Appropriate amounts of P, coupled with sufficient Zn, increased P and Zn concentrations in wheat grain. The Zn supply decreased both phytic acid and the molar ratios of phytic acid to Zn in wheat grain with respect to the Zn₀ treatment. Furthermore, proportions of Zn and P content in the grain relative to that of the whole plant were improved. With increasing P, the proportion of Zn and P content in the grain relative to the whole plant decreased. P and Zn acted antagonistically in roots. Excess P inhibited Zn uptake in roots, while Zn decreased the transfer of P from roots to shoots. For P that had been transported to the shoots, supplemental Zn facilitated its transfer to the grain. CONCLUSION: Excess P decreased the distribution of Zn in grain, while Zn enhanced the uptake of Zn and P in grain, The combined application of Zn fertilizer with the extensive use of P fertilizer can effectively increase the P and Zn concentration and Zn bioavailability of wheat grain, and hence Zn nutritional quality. Copyright © 2011 Society of Chemical Industry     

Mycorrhizal colonization and grain Cd concentration of field‐grown durum wheat in response to tillage,preceding crop and phosphorus fertilization

BACKGROUND: A 3‐year field trial was conducted to investigate the effect of agricultural management practices including tillage, preceding crop and phosphate fertilization on root colonization by arbuscular mycorrhizal (AM) fungi and grain cadmium (Cd) concentration of durum wheat (Triticum turgidum L.). The relationship between grain Cd and soil and plant variables was explored to determine the primary factors affecting grain Cd concentration. RESULTS: Mycorrhizal colonization of the roots was reduced by conventional tillage or when the preceding crop was canola (Brassica napus L.), compared to minimum tillage or when the preceding crop was flax (Linum usitatissimum L.). In contrast, grain Cd was not consistently affected by any treatment. Grain Cd was generally below the maximum permissible concentration (MPC) of 100 µg Cd kg^?1 proposed by WHO. Grain Cd varied substantially from year to year, and could be predicted with 70% of variance accounted for by using the model: grain Cd concentration = ? 321.9 + 44.5× ln(grain yield) + 0.26× soil DTPA‐Cd + 182.5× soil electrical conductivity (EC)? 0.98× grain Zn concentration. CONCLUSIONS: These common agricultural management practices had no effect on grain Cd concentration in durum wheat though they impacted mycorrhizal colonization of roots. Grain yield and to a lesser extent soil conditions of EC and DTPA‐Cd and grain Zn influenced grain Cd, whereas mycorrhizal colonization levels did not. Copyright © 2010 Crown in the right of Canada. Published by John Wiley & Sons, Ltd     

Changes in the efficiency of fertiliser use in China

Results of three nationwide fertiliser efficiency studies in recent history in China are reviewed. The results indicate that after a long history using organic recycling to maintain soil fertility in China, nitrogen (N) became the first yield-limiting nutrient in the first national fertiliser efficiency study in 1935-1940. With N fertilisation being used, phosphorus (P) and potassium (K) deficiencies were gradually revealed and developed in the following national fertiliser efficiency studies in 1958-1962 and 1981-1983. Research conducted through the International Plant Nutrition (IPNI) cooperative network in China in 2000-2006 indicates that agronomic efficiencies of N fertiliser (yield increase per kilogram from the application of 1 kg N) for rice, wheat and maize are 11.7 kg, 10.8 kg and 12.2 kg grain per kilogram of N, respectively, while crop recovery efficiency of N (percentage of N taken up by plant in total N applied) with rice, wheat and maize were 24.8%, 35.7% and 30.5%, respectively. Both agronomic efficiency and crop recovery efficiency of N are significantly lower than the average N use efficiency reported in international literature for other countries. Current agronomic efficiency of P and K are also discussed. Measures to improve fertiliser use in China are discussed.     

Effects of husbandry treatments on nitrogen concentration of grain and related yields in winter-wheat experiments made in South-East England

Experiments by Rothamsted staff over 20 years show that N (protein) concentration in wheat grain is influenced considerably by several husbandry treatments other than total fertiliser N. Even small differences can be of practical importance if values lie close to the minimum standard for bread wheat. In 15 experiments which tested timing of fertiliser N, an extra 60 kg ha^?1 would have been needed in autumn to increase grain-N concentration by 0.1% on average, but only 43 kg in early and 30 kg in late spring. The response to autumn N was similar in a ley-arable rotation experiment Fertiliser N applied to a previous potato crop gave a grain-N% increase equivalent to a quarter of the fresh application on a silty clay loam soil but none on a sandy loam. Cumulative annual dressings of farmyard manure benefited grain-N% as did residues from FYM applied to a previous potato crop, which gave increases equivalent to those from 16 kg ha^?1 of fresh fertiliser N. In ley-arable rotation experiments, wheat after arable cropping did not reach bread-quality standard with the largest amount of fertiliser N (150 kg ha^?1), but after lucerne N% values exceeded the threshold value of 2.14% N with all rates. Benefits from lucerne and a grass-clover ley were still considerable when wheat was grown as a second test crop after potatoes. Yield responses to these husbandry treatments tended to be small and positive, except that in the presence of larger dosager of fertiliser N farmyard manure sometimes caused a depression.     

Effects of iron and zinc foliar applications on rice plants and their grain accumulation and grain nutritional quality

BACKGROUND: Foliar sprays of iron (Fe) and zinc (Zn) fertilisers are known to be an effective way to improve Fe and Zn concentrations in rice grain. However, results can differ significantly among different rice cultivars and/or types of foliar fertiliser. In this study, several Fe‐rich rice cultivars were used to identify an effective foliar fertiliser for optimal Fe and Zn enrichment of rice grain. RESULTS: Foliar Fe amino acid (Fe‐AA) fertiliser significantly improved the Fe concentration in brown rice of most cultivars. Compared with the control, the average Fe concentration in all tested cultivars was increased by 14.5%. The average Fe concentration was increased by 32.5% when 1% (w/v) nicotianamine (NA) was added to Fe‐AA, while the average Zn concentration was increased by 42.4% when 0.5% (w/v) ZnSO₄ · 7H₂O was added to Fe‐AA. CONCLUSION: The results suggested that NA at a suitable concentration added to Fe‐AA fertiliser could accelerate Fe accumulation in rice grain. A relatively low concentration of ZnSO₄ · 7H₂O added to Fe‐AA significantly increased Fe and Zn accumulation in rice grain. The study identified some useful foliar fertilisers for enhancing the levels of Fe and Zn in selected Fe‐rich rice cultivars. Copyright © 2012 Society of Chemical Industry     

Using dual‐purpose crops in sheep‐grazing systems

The utilisation of dual‐purpose crops, especially wheat and canola grown for forage and grain production in sheep‐grazing systems, is reviewed. When sown early and grazed in winter before stem elongation, later‐maturing wheat and canola crops can be grazed with little impact on grain yield. Recent research has sought to develop crop‐ and grazing‐management strategies for dual‐purpose crops. Aspects examined have been grazing effects on crop growth, recovery and yield development along with an understanding of the grazing value of the crop fodder, its implications for animal nutrition and grazing management to maximise live‐weight gain. By alleviating the winter ‘feed gap’, the increase in winter stocking rate afforded by grazing crops allows crop and livestock production to be increased simultaneously on the same farm. Integration of dual‐purpose wheat with canola on mixed farms provides further systems advantages related to widened operational windows, weed and disease control and risk management. Dual‐purpose crops are an innovation that has potential to assist in addressing the global food‐security challenge. © 2013 Society of Chemical Industry     

Cadmium concentration in durum wheat grain (Triticum turgidum) as influenced by nitrogen rate,seeding date and soil type

BACKGROUND: Cadmium (Cd) is a trace element that has been associated with various human health problems. Cd enters plants, either by direct absorption through leaves or by uptake from soils, allowing Cd into the food chain. Nitrogen (N) fertilizer management is important in optimizing crop yield and protein content of durum wheat, but may influence Cd availability and hence Cd concentration in crops, with the effects being strongly influenced by environmental conditions and crop cultivar. RESULTS: In field studies, Cd and protein concentration in durum wheat grain differed between cultivars and were strongly affected by N application, with only minor effects of N occurring on concentration and uptake of P and Zn. Protein content increased significantly with N application in five of six site‐years, with the response being generally independent of cultivar and seeding data. Cd concentration also increased with N application in five of six seeding dates, with the response being greater in AC Melita than Arcola in three of the six site‐years. There were large differences in Cd concentration from year to year and with seeding date, indicating a strong environmental influence. CONCLUSIONS: This study shows that different cultivars accumulate different levels of Cd in the grain and that seeding date and nitrogen fertilizer management can influence grain Cd concentration, with the magnitude of effects varying with environmental factors. In the future we may be able to manipulate management practices to optimize protein concentration and minimize Cd concentration in durum wheat, which could help to address the health and safety concerns of consumers. © Society of Chemical Industry and Her Majesty the Queen in right of Canada     

Impact of a polyethylene liner on the storage of winter canola seed in unaerated steel bins

Winter canola has potential as a rotational crop for small cereal grains throughout the southern United States. However, canola is typically harvested just before wheat and is not yet considered a primary crop in the south. This combined with already tight storage capacity has led producers and facility managers to look for ways to press older, low-quality storage bins into service. One idea has been the use of grain bag material as a liner for older bins that lack functional aeration systems. This project compared the storage quality of canola in lined and unlined steel grain bins without aeration. There was not a significant difference in storage quality between the lined and unlined bins. Canola seed at 5.4% moisture content was stored without loss in grade for eleven months. Lining the entire bin with grain bag material does not appear to be justified, however, there may be merit in lining the bottom of older grain storage bins to prevent moisture intrusion.     

Nitrogen availability drives the effect of Glomus intraradices on the growth of strawberry (Fragaria x ananassa Duch.) plants

BACKGROUND: On the one hand, the critical nitrogen (N) content curve allows the minimal N content necessary for maximum growth rate at any stage of crop development to be predicted. On the other hand, arbuscular mycorrhizal fungi (AMF) transfer N from the soil to the plants and its growth and activity depends on the availability of soil N. Our objective was to investigate how the availability of N in the soil affects growth and the accumulation of N in inoculated strawberry plants. Root colonisation, dry matter accumulation and the critical N% curve were studied during growth of inoculated and non‐inoculated strawberry plants grown at several N levels. RESULTS: (1) The increase in the availability of N augmented root colonisation by AMF. (2) The effect of AMF on plant growth depended on N availability and the plant developmental status. (3) The critical %N curves were fitted by the following equations: %N = 2.81× (DM)^−0.21 (r² = 0.81) and %N = 2.89× (DM)^−0.32 (r² = 0.80) for inoculated and non‐inoculated plants, respectively (where DM is the weight of leaf dry matter, in g plant⁻¹). CONCLUSION: N availability was a key factor for root colonisation by AMF and for its contribution to plant growth. The patterns of the critical %N curves suggest that AMF modified the photosynthetic N use efficiency. Copyright © 2012 Society of Chemical Industry     

Effects of phosphorus and zinc fertilizer on cadmium uptake and distribution in flax and durum wheat

Cadmium accumulation in crops presents a potential risk to human health. To understand the difference between dicotyledonous and monocotyledonous species in respect of Cd accumulation, and to develop fertilizer management practices to minimise Cd uptake, a growth chamber study was conducted to evaluate the interactive effects of Cd concentration in phosphate and Zn fertilizer on Cd uptake in flax (Linum usitatissimum L) and durum wheat (Triticum turgidum L). Cadmium concentration was higher in flax than durum wheat shoots. Cadmium concentration was lower and Zn concentration higher in the flax seed and durum wheat grain than in the root, shoot or straw of both species. These results suggest that flax has comparatively ineffective barriers discriminating against the transport of Cd from the root to the shoot via the xylem, and that both crops may restrict Cd translocation to the seed/grain via the phloem. Commercial grade monoammonium phosphate (NH₄H₂PO₄) or triple superphosphate (Ca(H₂PO₄)₂) produced higher seed Cd concentrations than did reagent grade P in flax but not in durum wheat. Application of P significantly decreased seed/grain Zn concentration and increased seed/grain Cd concentration. Zinc addition at 20 mg Zn kg^?1 soil with P decreased seed/grain Cd concentration (average 42.2% for flax, 65.4% for durum wheat), Cd accumulation (average 37.2% for flax, 62.4% for durum wheat) and Cd translocation to the seed/grain (average 20.0% for flax, 34.5% for durum wheat) in both crops. These results indicate that there is an antagonistic effect of Zn on Cd for root uptake and distribution within the plant. Copyright © 2004 Society of Chemical Industry     

Influences of weather,cultivar and fertiliser rate on grain protein polymer accumulation in field‐grown winter wheat,and relations to grain water content and falling number

BACKGROUND: The reasons for variations in the amount and size distribution of polymeric protein in mature wheat, related to bread‐making quality, are not fully understood and can be sought during the protein polymer formation period of grain maturation. The present study was aimed at investigating the accumulation and polymerisation of grain storage proteins during grain maturation and their relations to changes in falling number and grain water content in four cultivars of field‐grown winter wheat. RESULTS: Proteins were accumulated and polymerised similarly during grain development independently of cultivation environment, cultivar and fertiliser rate. A 3–6 day delay in maturity among cultivars led to a 3–12 day delay in protein accumulation during early grain development. An increase in nitrogen fertiliser rate from 160 to 200 kg N ha^?1 resulted in a 20% increase in the amount of sodium dodecyl sulfate (SDS)‐unextractable protein. Precipitation just before grain harvesting led to 40–50% increases in grain water content and 8–34% decreases in the amount of SDS‐unextractable monomeric protein. At increased grain water contents the fertiliser rate was negatively related to the amount of grain SDS‐unextractable protein. CONCLUSION: Accumulation and polymerisation of grain storage proteins are predetermined events in wheat. Grain moisture content is negatively related to grain storage protein polymerisation, although the rate of decrease is influenced by the fertiliser regime. Copyright © 2008 Society of Chemical Industry     

Nutrient use efficiency and arbuscular mycorrhizal root colonisation of winter wheat cultivars in different farming systems of the DOK long‐term trial

BACKGROUND: For organic farming, cultivars are required with high nutrient use efficiency under nutrient limited conditions. Arbuscular mycorrhizal fungi (AMF) are known to contribute to nutrient uptake under low input conditions. We compared nutrient use efficiency (NUE) of old and modern organically and conventionally bred cultivars in organic and conventional systems and assessed AMF‐root colonisation (AMF‐RC) in relation to nutrient concentrations. RESULTS: Cultivars and systems had a statistically significant effect on nitrogen (N) and phosphorus (P) concentrations and NUE parameters, whereas no genotype × environment interactions appeared. In contrast to N and P uptake, the NUE parameters were higher under organic than under conventional conditions. NUE for N increased with the year of release of cultivars. In the organic systems, the organically bred cultivars could not outperform the conventionally bred cultivars in grain yield and NUE parameters. AMF‐RC was higher in the organic than in the conventional system, but did not differ among cultivars. CONCLUSION: Cultivars achieving high NUE in the organic systems were found among modern cultivars, irrespective of the breeding programme. Nutrient conditions during the breeding programme did not affect AMF‐RC. No clear evidence was found that AMF symbiosis contributed more to nutrient concentrations under low input than under high input conditions. Copyright © 2010 Society of Chemical Industry     

No tillage affects the phosphorus status,isotopic composition and crop yield of Phaseolus vulgaris in a rain‐fed farming system

BACKGROUND: Conservation tillage promotes the accretion of soil organic matter and often leads to improved soil fertility and moisture availability. However, few studies have looked at the physiological response of crop plants to different tillage practices. It was therefore hypothesised that measuring the nutrient concentrations and stable isotope composition (δ¹³C, δ¹⁸O, δ¹⁵N) of shoots could help evaluate the physiological response of common bean (Phaseolus vulgaris L.) to different tillage treatments (no tillage (NT) and mouldboard ploughing (MP)) in a rain‐fed farming system in northern Mexico. RESULTS: NT significantly enhanced shoot phosphorus concentration in bean plants. Tillage exerted a negative effect on the extent of root colonisation (%) by arbuscular mycorrhizal fungi (AMF). Lower shoot δ¹⁸O but unchanged δ¹³C values in plants from the NT system suggest enhanced stomatal conductance but also enhanced photosynthetic rate, which overall resulted in unchanged water use efficiency. Bean plants in the NT system showed lower shoot δ¹⁵N values, which suggests that a larger proportion of total plant nitrogen was obtained through atmospheric nitrogen fixation in this treatment. CONCLUSION: Greater diversity of AMF soil communities and heavier colonisation of roots by AMF in the NT compared with the MP system appeared to contribute to improved crop nutrition, water relations and yield in this rain‐fed agroecosystem. Copyright © 2010 Society of Chemical Industry     

Using estimated nutrient intake from pasture to formulate supplementary concentrate mixes for grazing dairy cows

In pasture-based dairy systems, feeding a complex concentrate mix in the parlor during milking that contains cereal grains and protein supplements has been shown to have milk production advantages over feeding straight cereal grain. This experiment had the aim of testing whether further milk production advantages could be elicited by adjusting the composition of the concentrate mix in an attempt to match the expected nutrient intake from pasture during late spring. The experiment used 96 lactating dairy cows, grazing perennial ryegrass pasture offered at a target allowance of 30 kg of dry matter/cow per day (to ground level) during late spring (mid October to November) in southeastern Australia. Cows were allocated into 3 replicates of 4 treatment groups, with 24 cows in each treatment. Each treatment group was offered 1 of 4 dietary treatments in the parlor at milking: control consisting of crushed wheat and barley grains; formulated grain mix (FGM) consisting of crushed wheat, barley, and corn grains and canola meal; designer grain mix 1 (DGM1) consisting of the same ingredients as the FGM grain mix but formulated using the CPM Dairy nutrition model to take into account the expected nutrient intake from pasture; and designer grain mix 2 (DGM2) consisting of the same ingredients as DGM1 but with canola meal replaced by urea and a fat supplement (Megalac, Volac Wilmar, Gresik, Indonesia). Concentrate mixes were offered at 8.0 kg of dry matter/cow per day, except for DGM2 cows, which were offered 7.5 kg of dry matter/cow per day. The experiment ran for a total of 28 d; after a 14-d adaptation period, nutrient intake, milk production, and body weight were measured over a 14-d measurement period. Milk yield (kg) of cows fed the FGM diet was greater than that of the control cows but was not different from that of the DGM1 and DGM2 cows. However, milk fat and protein yields (kg) were greater for cows fed the FGM diet than for all other diets. There was no difference in estimated daily pasture or total dry matter intakes between the 4 treatment groups, despite cows fed the DGM2 treatment consuming less of the concentrate mix (average 6.5 kg of dry matter/cow per day when offered 7.5 kg of dry matter/cow per day). This research has demonstrated the potential for using a nutrition model to take into account the expected nutrient intake from pasture to formulate a concentrate mix (DGM1) to achieve similar milk yields, but also highlighted the need for near real-time analyses of the pasture to be grazed so as to also capture benefits in terms of milk fat and protein yield.     

Effect of drought and irrigation on the fate of nitrogen applied to cut permanent grass swards in lysimeters: Nitrogen balance sheet and the effect of sward destruction and ploughing on nitrogen mineralisation

Fuor years after ¹⁵N labelled fertiliser nitrogen (as Ca(NO₃)₂ and equivalent to 400 kg N ha^?1) was applied to permanent grass swards growing in lysimeter monoliths, approximately one-quarter remained immobilised in soil organic matter. In the intervening years similar but non-labelled applications were made. Although differing rainfall regimes applied during the experiment had significantly affected nitrogen uptake by plants and nitrate loss in drainage, they caused no significant effect on the tracer nitrogen remaining in the soil, the ranges were 85–97 kg N ha^?1 and 79–94 kg N ha^?1 respectively for the 135 cm deep clay and silt loam soil monoliths. Labelled nitrogen unaccounted for in crop, drainage or soil was presumed to have been denitrified. These losses averaged 62 and 49 kg N ha^?1 on the clay and silt loam soils respectively; again the differing rainfall regimes caused no significant differences. The ratio between estimates of labelled nitrogen denitrified and of annual nitroux oxide loss was approximately 9:1 for both soils. The conversion from permanent grass to winter wheat in autumn 1981, involving killing and then burying the sward, resulted in no pronounced increase in net mineralisation of labelled nitrogen. However, the balance between crop uptake and the quantity leached did change. Labelled nitrogen assimilated was less for the wheat (growing without addition of fertiliser nitrogen) than for the grass in its last year, and the quantity leached was considerably greater than under grass swards that were supplied with an average rainfall distribution. Following the first wheat harvest total nitrogen leached averaged 51 and 44 kg N ha^?1 on the clay and silt loam soils respectively. Rates of nitrous oxide emissions during the autumn following sward destruction were greater than in earlier years, but this enhanced loss was of short duration. The crop clearly benefited from the succession of nitrogen applications made to grass, as grain yield and total nitrogen uptake exceeded 7 t ha^?1 and 120 kg N ha^?1 respectively on both soils. These quantities exceed the national averages for winter wheat and are also considerably greater than for crops from lysimeters which received no nitrogen fertiliser throughout the experiment.     

The effect of the previous crop on the growth,nitrogen uptake and yield of winter barley intended for malting

Winter barley which received a range of nitrogen rates, was grown at Rothamsted as a test crop after winter oats, winter barley, winter beans, oilseed rape or potatoes, to compare the effects of previous crop on growth and N uptake. In the autumn following the first year crops, the largest amount of residual inorganic N found in the soil was after potatoes, the smallest after oats. Throughout the second season the heaviest crops of barley, which also contained the most N, were after potatoes, and the lightest were after barley. To produce grain with a N concentration of less than 1.8% N (w/w, dry wt), acceptable for malting, it was found that not more than 75 kg N ha⁻¹ after barley and 125 kg N ha⁻¹ after oats, 100 kg N ha⁻¹ after beans and 50 kg N ha⁻¹ after rape or potatoes could be applied. The results demonstrated that barley of acceptable quality for malting can be grown after a break crop, providing that the rate of N fertiliser is suitably adjusted to take account of the residual fertility, but the results do not suggest that residual soil N affects the grain N concentration differently to N applied as fertiliser early in the season.     

Iron, Zinc, and Protein Bioavailability Proxy Measures of Meals Prepared with Nutritionally Enhanced Beans and Maize

ABSTRACT:  Nutritionally enhanced beans (NEB) with more Fe and Zn than conventional beans (CB) and nutritionally enhanced maize (NEM) with more tryptophan and lysine than conventional maize (CM) were developed as part of a crop-biofortification strategy to improve human nutrition. Proxy measures were used to assess Fe and Zn bioavailability and protein digestibility of a bean recipe ( fríjol sancochado ) and a maize–milk recipe ( mazamorra ) prepared with enhanced or conventional crops in Colombia. Fe concentration was similar in the cooked NEB and CB and in NEM and CM ( P ≥ 0.05); in vitro Fe dialyzability was similar in cooked NEB (9.52%) and CB (9.72%) and greater for NEM (37.01%) than CM (32.24%). Zn concentration was higher in the uncooked and cooked NEB than in the CB ( P < 0.05); phytate: Zn molar ratios were high in cooked NEB (36: 1) and CB (47: 1), suggesting low Zn bioavailability, and not different from each other ( P  = 0.07). There were no differences in Zn concentration or phytate: Zn molar ratio in the maize recipes. Nitrogen, tryptophan, and lysine concentrations were higher in the cooked NEM than CM; nitrogen was higher in the cooked NEB than CB ( P < 0.05). In vitro protein digestibility was comparable (82% to 83%) for NEM and CM and higher for NEB (84%) than for CB (82%). The higher nutrient concentrations + similar bioavailability (protein in NEM, Zn in NEB), same nutrient concentrations + higher bioavailability (Fe in NEM) or higher nutrient concentrations + higher bioavailability (protein in NEB) can translate into more nutrients absorbed and utilized by the body.     

Can iron and zinc in rice grains (Oryza sativa L.) be biofortified with nitrogen fertilisation under pot conditions?

BACKGROUND: Because only grain yield has been investigated, the influence of fertilisation by N on the concentration of Fe and Zn in polished rice has been overlooked in China. So, using the rice cultivars of the indica Zhenong 952 and the japonica Bing 98110, pot experiments were conducted to investigate the amounts of N fertiliser (applied as urea at rates of 0, 0.50, 1.00 and 1.50 g N pot^?1) that would lead to the optimum Fe and Zn concentrations in polished rice as well as grain yield. RESULTS: For Zhenong 952, the optimal Fe and Zn concentration as well as grain yield was attained at a N application of 1.00 g pot^?1; for Bing 98110 the optimum N was 1.50 g pot^?1. The ratio of Zn deposited in brown rice was about 40% of the total Zn in the plant irrespective of N application. However, Fe was only about 3%. Fe concentration in brown rice was approximately one‐half of the rice husk, one‐fifth of the peduncles, and one‐tenth of the leaves, and a little more than 1% of the root. CONCLUSION: The optimum N application, alone, on rice crops could increase Fe concentration in polished rice, but had an adverse effect for Zn. Fe appeared not to be as easily accumulated into rice seeds as was Zn. Copyright © 2008 Society of Chemical Industry