Organic Maize Research Articles

Coexistence in Maize: Effect on Pollen‐Mediated Gene Flow by Conventional Maize Border Rows Edging Genetically Modified Maize Fields

ABSTRACTIn addition to or as substitution for a regulated isolation distance, conventional maize (Zea mays L.) border rows at the genetically modified (GM) maize field edge are considered as feasible measure to ensure coexistence between GM and conventional or organic maize. Therefore, we examined the effectiveness of 9‐m‐ and 18‐m‐wide non‐GM maize borders at the GM maize field edge on outcrossing rates into a neighboring non‐GM maize field. One field experiment each was conducted in 2008 at three sites in Germany using a field orientation representing a worst‐case scenario concerning wind direction. In each case, the distance between GM and non‐GM maize fields was 51 m. At two sites, sizes of GM and non‐GM maize fields were 0.8 ha, respectively, and at the third site 0.5 ha (GM) and 0.3 ha (non‐GM). The GM percentages of individual samples taken at recipient field depths between 0 and 90 m were quantified by real‐time polymerase chain reaction. Overall, no pollen‐mediated gene flow reducing effect of border rows was observed in the present study, although synchrony of anthesis between GM maize and border row maize was given at each site. Calculated GM contents of the total non‐GM fields harvest were always below the European Union labeling threshold of 0.9%. In consequence, planting 9‐m‐ or 18‐m‐wide conventional maize border rows at the GM field edge is no reliable coexistence measure, at least if combined with an isolation distance.

Exploration of Islamic medicine plant extracts as powerful antifungals for the prevention of mycotoxigenic Aspergilli growth in organic silage

Feed contamination with mycotoxins is a major risk factor for animals and humans as several toxins can exist as residues in meat and milk products, giving rise to carry-over to consumers via ingestion of foods of animal origin. The starting point for prevention, in this chain, is to eliminate the growth of mycotoxigenic fungi in the animal forage. Ten plant extracts, recommended in Islamic medicine, were evaluated as antifungal agents against mycotoxigenic Aspergilli, i.e. Aspergillus flavus and A. ochraceus, growth in organic maize silage. Most extracts had remarkable antifungal activities using both qualitative and quantitative evaluation methods. Cress (Lepidium sativum) seed extract was proven to be the most powerful among the plants examined. Blending of the most effective extracts (garden cress seed, pomegranate peel and olive leaf extracts), individually at their minimal fungicidal concentrations, with maize silage resulted in the reduction of inoculated A. flavus colony counts by 99.9, 99.6 and 98.7%, respectively, whereas silage blending with the combined extracts completely prohibited fungal growth for up to 30 days of incubation under aerobic conditions. Besides the health promoting effects, silage blending with the bioactive plant extracts examined could lead to the required protection from pathogenic and mycotoxigenic fungi.

Efficacy of modified atmosphere packaging to control Sitophilus spp. in organic maize grain

The effect of modified atmosphere packaging on the mortality of Sitophilus spp. in organic maize grain was studied. Maize grains were packed with five different atmospheres consisting of 20% O2, or 20, 40, 60, 80% CO2 with remaining N2. The packages were stored for 30 days at 26°C. CO2 and O2 concentrations were monitored inside the packages during the storage. The moisture content, titratable acidity and pH were analysed on the first and thirtieth day. At 5, 15 and 30 days of storage no significant differences were observed in the percentages of dead insects when CO2 was used. The results of progeny indicated that from the fifth day the number of emerging insects was low at 20, 60 and 80% CO2. Complete inhibition of the insects was achieved with 30 days of exposure in CO2 atmospheres.

Organic Maize Growth and Mycorrhizal Root Colonization Response to Tillage and Organic Fertilization

The influence of conventional and no-tillage on mycorrhizal root colonization, soil properties and yield, was studied for 2 years in an experimental field of organic maize, fertilized by cattle manure or by seaweed compost. The no-tillage system improved soil macroporosity, increased organic carbon content, and enhanced the mean weight diameter of soil aggregates. Similarly, it had a positive effect on plant growth. Root density, leaf area index, biomass, grain yield and mycorrhizal root colonization were significantly affected by tillage system. Fertilization with manure and compost improved soil structure and aeration, thus favoring a higher mycorrhizal colonization of organic maize. The improved soil physical properties were positively related to mycorrhizal root colonization. High correlation coefficients of determination (r2) were also found between mycorrhizal root colonization and plant characteristics. It is concluded that the no-tillage system can improve the productivity of organic agriculture via pronounced arbuscular mycorrhizal root colonization.

Maize response to broadcast flaming at different growth stages: Effects on growth, yield and yield components

Weed management is a major constraint in organic crop production. Propane flaming could be an additional tool for weed control in organic maize ( Zea mays L.) production. However, tolerance of maize to broadcast flaming must be determined first to optimize the use of propane. Field experiments were conducted at the Haskell Agricultural Laboratory of the University of Nebraska, Concord, NE in 2008 and 2009 to determine maize response to five propane doses applied at three growth stages of V2 (2-leaf), V5 (5-leaf) and V7 (7-leaf). The propane doses tested were 0, 13, 24, 44 and 85 kg ha −1. Flaming treatments were applied utilizing a custom built research flamer mounted on the back of a four-wheeler moving at a constant speed of 6.4 km h −1. The response of maize to propane flaming was evaluated in terms of visual crop injury (1, 7, 14 and 28 days after treatment—DAT), effects on dry matter (14 DAT), yield components (plants m −2, ears plant −1, kernels cob −1 and 1000-kernel weight) and grain yield. The response of different growth stages of maize to propane doses was described by log–logistic models. Overall, maize response to broadcast flaming varied among growth stages and propane doses. In general, maize at V5 was the most tolerant stage for broadcast flaming, whereas V2 stage was the most susceptible to flaming resulting in the highest visual crop injury ratings, dry matter reductions and the largest loss of yield and its components. At 28 DAT, the maximum visual crop injury rating of 7% was estimated for flaming done at V5 stage compared to significantly higher injuries of 43% and 12% for V2 and V7 growth stages, respectively. An arbitrarily assigned 2.5% yield reduction was evident with 33, 16 and 11 kg ha −1 of propane for V5, V2 and V7 growth stages, respectively, suggesting that maize flamed at V5 stage can tolerate higher dose of propane for the same yield reduction compared to other growth stages. Moreover, the maximum yield reductions with the highest propane dose of 85 kg ha −1 were 3% for V5, 11% for V7 and 17% for V2 stage. Based on these results, flaming has a potential to be used effectively in organic maize production when conducted properly at V5 stage. However, there are both benefits and concerns associated with the use of flame weeding. The preservation of the soil from erosion and the protection of the surface and underground water from chemical pollution can be seen as benefits, while the concerns include higher energy use, and the release of greenhouse gasses.

Compost Effect on Plant Growth-Promoting Rhizobacteria and Mycorrhizal Fungi Population in Maize Cultivations

The composting process allows the conversion of organic waste into organic matter that can be used in counteracting organic matter soil depletion. Moreover, agricultural use of compost increases plants defense abilities against pathogens, leading to a higher crop yield. Key plant growth-promoting rhizobacteria (PGPR) and arbuscular mycorrhial fungi (AMF) populations were evaluated after incorporating high quality composts in both conventional and organic maize production in order to determine if compost application affects the presence of important PGPR and AMF. Results obtained indicate that while the use of the compost as an amendment may exert a limited influence on AMF population, it can significantly modulate the composition of PGPR in the rhizosphere of maize plants.

Monitoring of Bt-Maize pollen exposure in the vicinity of the nature reserve Ruhlsdorfer Bruch in northeast Germany 2007 to 2008

Monitoring of Bt-Maize pollen exposure in the vicinity of the nature reserve Ruhlsdorfer Bruch in northeast Germany 2007 to 2008

Elucidating the apparent maize tolerance to weed competition in long‐term organically managed systems

Ryan MR, Mortensen DA, Bastiaans L, Teasdale JR, Mirsky SB, Curran WS, Seidel R, Wilson DO & Hepperly PR (2010). Elucidating the apparent maize tolerance to weed competition in long‐term organically managed systems. Weed Research50, 25–36.SummaryIn a long‐term cropping systems trial comparing organically and conventionally managed systems, organic maize production sustained crop yields equal to conventional methods despite higher weed levels. In 2005 and 2006, an experiment nested within the trial was conducted to gain insight into this apparent crop tolerance to weed competition. Density of mixed weed species was experimentally manipulated to achieve a broad range of weed infestation levels. Under standard management conditions, all cropping systems produced equivalent maize yields, even though weedy plant biomass in the organic treatments was between fourfold and sevenfold greater than in the conventionally managed maize. Increased yield capacity, evidenced when plots were maintained weed‐free, and enhanced crop competitiveness, were the main pillars of this apparent crop tolerance to weed competition in the organic systems. Increased soil resource availability and a faster relative crop growth rate in the organic systems probably contributed to these factors, which play an important role in buffering crop fitness during years of less than ideal weed control. Simultaneously, the experiment illustrated the poor efficacy of mechanical weed management in the organic systems, which is the main reason organic maize did not out‐yield conventional maize under standard management conditions.

Effects of Cultural System (Organic and Conventional) on Growth, Photosynthesis and Yield Components of Sweet Corn (Zea mays L.) under Semi-Arid Environment

Organic sweet maize consists of a new industrial crop product. Field experiment was conducted to determine the effects of cultural systems on growth, photosynthesis and yield components of sweet maize crop (Zea mays L. F1 hybrid Midas). A randomized complete block design was employed with four replicates per treatment (organic fertilization: cow manure (5, 10 and 20 t ha1), poultry manure (5, 10 and 20 t ha1) and barley mulch (5, 10 and 20 t ha1), synthetic fertilizer (240 kg N ha1): 21-0-0 and control). The lowest dry weight, height and leaf area index and soil organic matter were measured in the control treatment. Organic matter content was proportionate to the amount of manure applied. The control plots had the lowest yield (1593 kg ha-1) and the double rate cow manure plots the had greatest one. (6104 kg ha-1). High correlation between sweet corn yield and organic matter was registered. Moreover, the lowest values of 1000-grain weight were obtained with control plot. The fertilizer plot gave values, which were similar to the full rate cow manure treatment. The photosynthetic rate of the untreated control was significantly lower than that of the other treatments. The photosynthetic rate increased as poultry manure and barley mulch rates decreased and as cow manure increased. Furthermore, the untreated control had the lowest stomatal conductance and chlorophyll content. Our results indicated that sweet corn growth and yield in the organic plots was significantly higher than those in the conventional plots.

Propriedades químicas de um LATOSSOLO VERMELHO Eutroférrico após aplicação por dois anos consecutivos de lodo de esgoto

O destino do lodo de esgoto é um dos problemas ambientais urbanos mais relevantes na atualidade. Assim, este trabalho teve por objetivo avaliar as propriedades químicas e a produtividade de milho safrinha em um LATOSSOLO VERMELHO Eutroférrico tratado com lodo de esgoto por dois anos consecutivos. As análises foram realizadas em um experimento instalado na Fazenda Escola da Universidade Estadual de Londrina, Estado do Paraná, que apresentava delineamento em blocos ao acaso, contendo 3 repetições com os seguintes tratamentos: sem adubação, somente adubação mineral, adubação orgânica com lodo de esgoto (em base seca) em doses crescentes de 6, 12, 18, 24 e 36 t.ha-1. Nas avaliações, foram determinados pH, teores de Ca2+, Mg2+, P, K+, CTC, V %, carbono orgânico e a produtividade do milho safrinha. Os resultados mostraram que a acidez do solo, a CTC, V%, os teores de Ca2+, Mg2+, P, carbono orgânico e a produtividade do milho safrinha aumentaram em função das doses de lodo aplicadas no solo, sendo os melhores resultados alcançados na parcela que recebeu 36 t.ha-1 / ano

Natural Occurrence of Fusarium Species, Fumonisin Production by Toxigenic Strains, and Concentrations of Fumonisins B1 and B2 in Conventional and Organic Maize Grown in Spain

Sixty samples of corn from both conventional and organic farms were tested for internal fungal contamination. Molds were identified to genus, and those belonging to the genus Fusarium were identified to species. Twenty isolates of Fusarium verticillioides were tested with a high-performance liquid chromatography–naphthalene dicarboxaldehyde–fluorescence method for their ability to produce fumonisins B1 and B2. The internal fungal infection in organic maize (63.20%) was significantly higher than that in conventional maize (40.27%) (P < 0.05). However, the distribution of fungal genera indicated a significantly higher prevalence of Fusarium in conventional (34.93%) than in organic (18.15%) maize, making Fusarium the predominant fungus in conventional maize. This difference in mold distribution between organic and conventional maize was attributed to the difference in cultivation system. The dominant Fusarium species in both conventional and organic samples was F. verticillioides. There were no significant differences in the ability of 20 selected isolates of F. verticillioides to produce fumonisins on conventional or organic corn. Up to 13.3% of the conventional corn samples contained fumonisins B1 and B2 at mean concentrations of 43 and 22 ng/g, respectively. Organic corn samples had somewhat lower levels of contamination: 35 ng/g fumonisin B1 and 19 ng/g fumonisin B2 (P > 0.05). The organic farming system, with well-balanced crop rotation, tillage, and compost fertilization, produced corn that was less likely to be contaminated with Fusarium species, although no significant difference in fumonisin concentrations was found between the two types of contaminated corn.

Estimation of dietary intakes of fumonisins B 1 and B 2 from conventional and organic corn

The dietary intakes of fumonisins from 60 samples of conventional and organic corn were assessed. A 13.3% of the conventional corn samples contained fumonisin B 1 and B 2 at mean levels of 43 and 22 ng/g, respectively, while 10% of the organic corn samples contained fumonisins at somewhat lower levels of 35 ng/g (FB 1) and 19 ng/g (FB 2). Overall, the fumonisin levels in the corn samples were much lower than the maximum level of 2000 ng/g (as the sum of FB 1 and FB 2) proposed for unprocessed maize in a recent EU regulation. The fumonisins present in conventional and organic maize are estimated to contribute with very low percentages of 0.21% and 0.17%, respectively, to the level considered at risk for human health. Based on the data exposed in this paper, the farming system is probably not of decisive importance for the final contamination of agricultural products with these mycotoxins.

Green mulch decomposition and nitrogen release from leaves of two Inga spp. in an organic alley-cropping practice in the humid tropics

Inga edulis Mart and Inga samanensis Uribe are promising yet little studied legume trees for use in agroforestry on acidic soils. The objective of this study was to analyze the decomposition and N release processes of green mulch from these species. Litterbags filled with leaves from each species were placed on the ground in an organic maize (Zea mays L.) alley-cropping experiment at the time of maize sowing and collected every 2 weeks over a 20 week period, and measured for dry matter, N, hemicellulose, cellulose, and lignin content. Three types of models were applied to the data, according to the characteristics of each component, to analyze the decomposition dynamics of whole leaves and leaf components: a negative exponential decay function, an inverted Michaelis‐Menten function, and a linear regression. Initial decay of I. samanensis mulch was faster than I. edulis mulch. However, the recalcitrant fraction was about half of the initial litter mass in both Inga spp. Hemicellulose disappeared almost completely from the litter during the 20week incubation period, while no significant lignin decay occurred. After a slow start, cellulose partially decayed following linear kinetics. The half-life of labile N, estimated as a Michaelis‐Menten parameter, was 10 weeks in I. samanensis and ca. 24 weeks in I. edulis litter. Polyphenol content was significantly higher in I. edulis. Litter of I. edulis and I. samanensis may be classified as ‘lowquality’ and ‘medium-quality’ mulch, respectively. Due to the relatively large recalcitrant mulch fraction, both Inga spp. may promote C sequestration and long-term N accumulation in soil. q 2005 Elsevier Ltd. All rights reserved.

Ford, B.J. (ed.) GM Crops: the scientists speak.

Ford, B.J. (ed.) GM Crops: the scientists speak.

Crop yields over the first nine years of LTRAS, a long-term comparison of field crop systems in a Mediterranean climate

The Long-Term Research on Agricultural Systems (LTRAS) experiment has been monitoring the long-term effects of conventional and alternative practices on crop yields and soil properties since 1993, with a planned duration of 100 years. Data for the first 9 years are presented here. Ten, 2-year rotations, each with three 0.4 ha plots per phase of the rotation, range from low-input rainfed unfertilized wheat to high-input irrigated conventional and organic maize–tomato systems. For years 3–9, average yields of alternative (organic and green manure) systems were significantly lower than those of comparable conventional systems, except that there were no significant differences in average yields of tomato. Delayed seeding after a winter legume cover crop (LCC) limited maize yields. Yield trends over years were somewhat obscured by variability due to weather. Negative yield trends over years in unfertilized wheat controls were statistically significant, but only when data for the 9th year were included. Yield trends for organic maize were also significantly negative, but tomato yields in the same system showed a significant positive trend, as did yields of conventional maize. As this experiment continues, long-term trends in soil properties and processes could alter the magnitude or direction of trends seen to date.

The performance of organic and conventional cropping systems in an extreme climate year

AbstractThe 1999 severe crop season drought in the northeastern US was followed by hurricane-driven torrential rains in September, offering a unique opportunity to observe how managed and natural systems respond to climate-related stress. The Rodale Institute Farming Systems Trial has been operating since 1981 and consists of three replicated cropping systems, one organic manure based (MNR), one organic legume based (LEG) and a conventional system (CNV). The MNR system consists of a 5-year maize–soybean–wheat–clover/hay rotation, the LEG of a 3-year maize–soybean–wheat–green manure, and the CNV of a 5-year maize-soybean rotation. Subsoil lysimeters allowed quantification of percolated water in each system. Average maize and soybean yields were similar in all three systems over the post-transition years (1985–1998). Five drought years occurred between 1984 and 1998 and in four of them the organic maize outyielded the CNV by significant margins. In 1999 all crop systems suffered severe yield depressions; however, there were substantial yield differences between systems. Organic maize yielded 38% and 137% relative to CNV in the LEG and MNR treatments, respectively, and 196% and 152% relative to CNV in the soybean plots. The primary mechanism of the higher yield of the MNR and LEG is proposed to be the higher water-holding capacity of the soils in those treatments, while the lower yield of the LEG maize was due to weed competition in that particular year and treatment. Soils in the organic plots captured more water and retained more of it in the crop root zone than in the CNV treatment. Water capture in the organic plots was approximately 100% higher than in CNV plots during September's torrential rains.

Effect of Organic Wastes and Method of Composting on Compost Maturity, Nutrient Composition of Compost and Yields of Two Vegetable Crops

ABSTRACT Two field experiments were carried out to evaluate the effect of composts prepared from different organic waste materials on two vegetable crops. Poultry litter with each of the following organic wastes, maize residues, leaf litter, urban waste, weed biomass and soybean residue, were composted using three methods of composting–Passively Aerated Composting Technique in a pile (PACT-1), Passively Aerated Composting Technique in a plastic pot (PACT-2) and Windrow (Wdr). Tomato (Lycosipercum esculentum Mill.) and amaranthus (Amaranthus cruentus) were planted as test crops. The C:N ratio and nutrient concentrations varied with type of organic waste materials. The leaf litter and weed biomass contained high C:N ratio (38 and 45, respectively) and therefore produced composts that matured a few weeks later than those from organic wastes with C:N ratio falling within the optimum range of 25-35. The C:N ratio of the organic wastes were highly reduced at the end of composting. Irrespective of method used for composting, N in the soybean-based compost increased by 37-71% over the concentrations in the other composts. Phosphorus in the leaf litter- and soybean-based composts increased by 13.6-34.9% over the level in the urban and weed-based composts. However, K levels in the maize- and weed-bio-mass based composts increased by 7-37% over other composts. Soybean- and leaf litter-based composts in general were greater in both secondary and micronutrient elements than other composts. The results from field evaluation indicated that the effectiveness of the composts on amaranthus productivity can be rated in the ascending order of soybean, leaf litter, weed, maize and urban waste composts. For tomato, the composts from maize and soybean residues were more effective than other composts. Mostly, the effectiveness of the composts on the productivity of the vegetable crops varied according to methods of composting and followed in the ascending order of Wdr, PACT-1 and PACT-2.

Effect of Organic matter application on the fate of 15N-labeled ammonium fertilizer in an upland soil

The effect of the application of organic matter on the fate of 15N-labeled ammonium was investigated in a field. The organic materials incorporated into the experimental plots consisted of wheat straw, rape, pig compost, cow compost, plant manure. In May 2000, 10 g N m−2 of 15N-labeled ammonium was applied to the field together with the organic materials, and maize and winter wheat were consecutively cultivated. The recovery of applied 15N in soils and plants was determined after the harvest of each crop. Although only about 10% of the applied 15N-labeled fertilizer remained in the 0-30 cm layer of the Control Plot and the Plant Manure Plot, more than 25% of the applied 15N remained in the Pig Compost Plot. Amount and proportion of the immobilized 15N to those of total N or microbial biomass N in soils were determined for the topsoil samples (0–10 cm layer). The amounts of both microbial biomass N and total immobilized 15N in soil were highest in the Pig Compost Plot. Although the amount of microbial biomass N was comparable to the amount of immobilized 15N-labeled fertilizer in soil, the amounts of 15N-labeled fertilizer contained in the microbial biumass accounted for less than 10% of the amount of total immobilized 15N in soil. The ratio of the amount of 15N-labeled fertilizer contained in biomass N to the total amount of biomass N was one order of magnitude higher than the ratio of the amount of immobilized 15N-labeled fertilizer to the amount of total N in soil. No conspicuous changes in the amount of immobilized 15N in soil were observed during the cultivation of winter wheat except for the Pig Compost Plot. No significant correlation was recognized between the amount of 15N-labeled fertilizer contained in microbial biomass before wheat cultivation and that of 15N-labeled fertilizer absorbed by wheat, indicating that microbial N immobilized during the growth period of the former crop (maize) was not a significant source of N for the latter crop (wheat).

Evaluation of combination of organic sources for organic maize (Zea mays) production

A field experiment was conducted during the rainy (kharif) seasons of 2013, 2014 and 2015 on red sandy loam soil of Mandya, to study the effect of different organic manures on growth and yield of maize (Zea mays L.) under irrigated condition in Cauvery Command Area of Karnataka.The experiment was laid out in a randomized com- plete-block design with 3 replications. There were 11 treatments, comprising different levels of compost manure equivalent (75, 100 and 125 kg N/ha) with FYM @ 10 t/ha, beejamrutha and jeevamrutha. The results indicated that, application of 100% N equivalent compost + FYM @ 10 t/ha + beejamrutha + Jeevamrutha @ 500 liter/ha re- corded significantly higher grain yield (6.13 t/ha), stover yield (7.84 t/ha), cob length (15.10 cm), number of leaves per plant (12.77) and plant height (226.0 cm), which was closely followed by application of 100% N equivalent compost + beejamrutha + jeevamrutha @ 500 litres/ha and 125% N equivalent compost + beejamrutha + jeevamrutha @ 500 litres/ha. Soil chemical properties, viz. soil pH, organic carbon content and electric conductiv- ity, were not influenced by application of the organic manures. However, there was an increasing trend in the soil chemical properties compared to initial soil data. However, application of 100% N equivalent compost + FYM @ 10 t/ha + beejamrutha + jeevamrutha recorded significantly higher available nitrogen, phosphorus and potassium content in the soil compared to the other treatments.

Amino Acid Composition of Grain Protein of Maize Grown with and without Pesticides and Standard Commercial Fertilizers1

AbstractIncreases in the price of agricultural chemicals and uncertain supplies are likely to cause a reduction of pesticide and fertilizer use in the future. Therefore, it is of interest to compare yields and quality of crops grown under present conventional practice with those grown at the lower limit of chemical intensiveness. In this paper, we report measurements of the amino acid composition of protein from maize (Zea mays L.) grain raised on 14 pairs of fields which did (conventional) and which did not (organic) receive pesticides and standard commercial fertilizers. The pairs of fields were matched for location, cultivar, planting date, and soil type.When expressed as percent of grain protein, five amino acids were at significantly higher concentration in organic grain and three were at significantly higher concentration in conventional grain. However, because of the lower protein concentration in the organic maize grain, most of the amino acids in conventional grain had significantly higher concentrations, when expressed as percent of total grain weight. The latter fact is more important from the standpoint of livestock feeding.Differences in yield, protein concentration, and amino acid composition between organic and conventional maize were qualitatively similar to reported differences between N‐fertilized and non‐N‐fertilized maize. At least part of the difference between organic and conventional maize is consistent with a greater accumulation of zein in conventionally raised maize.Results presented in this paper suggest that organic maize yields could be increased by N application. Since the yield difference was small, the N limitation should be overcome by modest rates of application.