Soybean Cropping Systems Research Articles

Effects of Conjunctive Use of Organic and Inorganic Sources of Nutrients on Soil Quality Indicators and Soil Quality Index in Sole Maize, Maize + Soybean, and Sole Soybean Cropping Systems in Hot Semi-arid Tropical Vertisol

The soils in the hot semi-arid tropical (SAT) regions generally have low organic matter and nutrient reserves. Soil-management problems in these soils primarily occur because of poor physical conditions and inadequate drainage through excess runoff, finally resulting in poor crop growth. Hence, the present investigation was conducted to study the long-term impact of conjunctive nutrient use treatments on soil quality indicators and soil quality indices under three cropping systems: (i) sole soybean, (ii) soybean + maize, and (iii) sole maize cropping systems at the Indore Centre of the All-India Coordinated Research Project for Dryland Agriculture (AICRPDA) using Navjot and JS-335 as cultivars of maize and soybean, respectively. In 2005, the soil quality assessment study under this experiment was undertaken after 8 years of experimentation. Soil quality assessment was done by identifying the key indicators using principal component analysis (PCA) and linear scoring technique (LST). Soil quality indices (SQI) and relative soil quality indices (RSQI) were also computed. Results revealed that most of the soil quality parameters were significantly influenced by the conjunctive nutrient management treatments. The common key indicators that emerged in all the treatments were pH, organic carbon (OC), exchangeable magnesium (Mg), available zinc (Zn), copper (Cu), manganese (Mn), and boron (B). The soil quality indices across the management treatments under sole maize system varied from 1.70 to 2.40 and application of 20 kg nitrogen (N) (compost) + 20 kg N through urea as top dressing emerged as a one of the most superior treatments with SQI value of 2.40. The soil quality indices in maize + soybean system varied from 1.12 to 1.47 and application of 20 kg N (compost) + 20 kg N through urea + azotobacter at 2 kg ha−1 proved to be significant with the greatest SQI value of 1.47. In the case of the sole soybean system, the SQI varied from 1.21 to 1.61. After considering all the systems together, the average best performance SQI score (ABP-SQI score) was computed, which varied from 1.14 to 1.56. The greatest value was recorded in the treatment with 20 kg N (compost) + 20 kg N (gliricidia) + 10 kg N (urea). The quantitative relationship developed in this study between mean soybean and maize yields (Y) and RSQI values (X), irrespective of the management treatments, could be quite useful to predict the yield quantitatively with respect to a given change in key indicators for these rainfed Vertisols.

Phosphorus and Potassium Transformations in Soil Amended with Enriched Compost and Chemical Fertilizers in a Wheat–Soybean Cropping System

India imports large amounts of rock phosphate (RP) and potassium (K) fertilizers from other countries; hence, research priorities have been directed toward finding alternative sources of phosphorus (P) and K fertilizers. This study focuses on the transformations of P and K in soil amended with RP and waste mica–enriched compost. The enriched compost had greater total P, K, calcium (Ca), magnesium (Mg), micronutrients, and biological properties than ordinary compost. In a wheat–soybean rotation, application of 5 t ha−1 enriched compost along with 50% of the recommended rate of inorganic fertilizer resulted in increased concentrations of saloid P, iron (Fe) P, aluminum (Al) P, Ca-P, occluded P, water-soluble K, exchangeable K, and nonexchangeable K over unfertilized plots. In addition, plots that received enriched compost had greater microbial biomass and phosphatase activities than unfertilized plots. Thus, enriched compost could be an alternative source of water-soluble P and K fertilizers for crop production.

SOIL FERTILITY STATUS AND SOYBEAN [Glycine max (L) Merr] PERFORMANCE FOLLOWING INTRODUCTION OF INDIGENOUS MYCORRHIZA COMBINED WITH VARIOUS NUTRIENT SOURCES INTO SANDY SOIL

Normal 0 false false false EN-US X-NONE X-NONE The experiment tested four treatments, namely inoculation of soil with mycorrhiza, inoculation of soil with mycorrhiza and cattle manure, inoculation of soil with mycorrhiza and rock phosphate, and inoculation of soil with mycorrhiza and inorganic fertilizers. Soil without any inoculation was provided as control. The treatments were arranged in a Completely Randomized Design with four replications. Soil fertility status was based on the concentrations of N, P, K, and organic-C as well as soil pH. Plant performance was determined based on its ability to uptake nutrients (N, P, K, and Ca), its growth and yield. Then, the activity of mycorrhiza was measured based on total population and percentage of root infection. Overall, results of the present study showed that, compared with other treatments, inoculation of mycorrhiza into soil and amended with cattle manure significantly performed higher concentrations of N, P, K, and organic-C. This soil condition caused soybean to absorb significantly higher nutrients, grew well with higher yield compared with plant performance in other treatments. Therefore, results of this study implies that the application of mycorrhiza into soil amended with organic matter is promising to sustain soil productivity under soybean cropping system. Keywords: Arbuscular Mycorrhiza, soil fertility, soybean yield, dryland /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif"; mso-ansi-language:EN-US; mso-fareast-language:EN-US;}

Impact of winter cover crops on soil properties under soybean cropping systems

Agricultural systems in Uruguay exhibit a high frequency of soybean in crop rotations. This could adversely affect soil organic carbon (SOC) storage in the long term. The introduction of winter annual cover crops (CC) in these systems may improve SOC balance as well as reduce the impact of rainfall on soil erosion rates. The objective of this study was to evaluate the impact of the inclusion of CC on SOC storage and soil physical properties under continuous soybean (Glycine max [L.] Merr) cropping systems. A field experiment was established in 2003 in a vertic Argiudoll. A split plot design was used with CC and non CC as whole plot arranged in four randomized complete blocks. Cover crops were: oats (Avena sativa L)., annual ryegrass (Lolium multiflorum L.). Two termination dates comprised split plots: 60 or 30 days before soybean planting. Mean annual forage production over eight years was higher (P ≤ 0.05) in oats compared to annual ryegrass for both termination dates. The inclusion of CC increased SOC concentration at the 0-7.5 cm depth, and at the 7.5-15 cm depth in the annual ryegrass treatment. Oats and annual ryegrass had 60 and 80 % more particulate organic carbon (POC) concentrations at the 0-7.5 cm, respectively than no cover crop treatment. No significant differences among treatments were observed for mineral associated organic C-MAOM at any depth. Nitrogen mineralization potential under ryegrass had a three-fold increase compared to the no cover crop treatment. Both CC treatments showed a higher (P ≤ 0.05) percentage of macropores compared to the no cover crop treatment. In most of the years soybean grain yield was not affected by cover crops treatments. However, late termination dates often reduced soybean yields. The inclusion of CC in high frequency soybean cropping systems may enhance soil C storage, and improve related soil physical properties.

Spectral Data-Based Estimation of Soil Heat Flux

Numerous existing spectral-based soil heat flux (G) models have shown wide variation in performance for maize and soybean cropping systems in Nebraska, indicating the need for localized calibration and model development. The objectives of this article are to develop a semi-empirical model to estimate G from a normalized difference vegetation index (NDVI) and net radiation (Rn) for maize (Zea mays L.) and soybean (Glycine max L.) fields in the Great Plains, and present the suitability of the developed model to estimate G under similar and different soil and management conditions. Soil heat fluxes measured in both irrigated and rainfed fields in eastern and south-central Nebraska were used for model development and validation. An exponential model that uses NDVI and Rn was found to be the best to estimate G based on r2 values. The effect of geographic location, crop, and water management practices were used to develop semi-empirical models under four case studies. Each case study has the same exponential model structure but a different set of coefficients and exponents to represent the crop, soil, and management practices. Results showed that the semi-empirical models can be used effectively for G estimation for nearby fields with similar soil properties for independent years, regardless of differences in crop type, crop rotation, and irrigation practices, provided that the crop residue from the previous year is more than 4000 kg ha-1. The coefficients calibrated from particular fields can be used at nearby fields in order to capture temporal variation in G. However, there is a need for further investigation of the models to account for the interaction effects of crop rotation and irrigation. Validation at an independent site having different soil and crop management practices showed the limitation of the semi-empirical model in estimating G under different soil and environment conditions.

Application of the Cropping System Model (CSM)‐CROPGRO‐Soybean for Determining Optimum Management Strategies for Soybean in Tropical Environments

AbstractThe determination of optimum crop management practices for increasing soybean production can provide valuable information for strategic planning in the tropics. However, this process is time consuming and expensive. The use of a dynamic crop simulation model can be an alternative option to help estimate yield levels under various growing conditions. The objectives of this study were to evaluate the performance of the Cropping System Model (CSM)‐CROPGRO‐Soybean and to determine optimum management practices for soybean for growing conditions in the Phu Pha Man district, Thailand. Data from two soybean experiments that were conducted in 1991 at Chiang Mai University and in 2003 at Khon Kaen University were used to determine the cultivar coefficients for the cultivars CM 60 and SJ 5. The CSM‐CROPGRO‐Soybean model was evaluated with data from two experiments that were conducted at Chiang Mai University. The observed data sets from farmers’ fields located in the Phu Pha Man district were also used for model evaluation. Simulations for different management scenarios were conducted with soil property information for seven different soil series and historical weather data for the period 1972–2003 to predict the optimum crop management practices for soybean production in the Phu Pha Man district. The results of this study indicated that the cultivar coefficients of the two soybean cultivars resulted in simulated growth and development parameters that were in good agreement with almost all observed parameters. Model evaluation showed a good agreement between simulated and observed data for phenology and growth of soybean, and demonstrated the potential of the CSM‐CROPGRO‐Soybean model to simulate growth and yield for local environments, including farmers’ fields, in Thailand. The CSM‐CROPGRO‐Soybean simulations indicated that the optimum planting dates from June 15 to July 15 produced maximum soybean yield in a rainfed environment. However, the planting date December 15 produced the highest yield under quality irrigation. Soybean yield was slightly improved by applying nitrogen at a rate of 30 kg N ha−1 at planting. Soybean yield also improved when the plant density was increased from 20 to 40 plants m−2. The results from this study suggest that the CSM‐CROPGRO‐Soybean model can be a valuable tool in assisting with determining optimum management practices for soybean cropping systems in the Phu Pha Man district and might be applicable to other agricultural production areas in Thailand and southeast Asia.

Biomass production and carbon stocks in poplar-crop intercropping systems: a case study in northwestern Jiangsu, China

The importance of agroforestry systems in CO2 mitigation has become recognized worldwide in recent years. However, little is known about carbon (C) sequestered in poplar intercropping systems. The main objective of this study is to compare the effects of three poplar intercropping designs (configuration A: 250 trees ha−1; configuration B: 167 trees ha−1 and configuration C: 94 trees ha−1) and two intercropping systems (wheat–corn cropping system and wheat–soybean cropping system) on biomass production and C stocks in poplar intercropping systems. The experiment was conducted at Suqian Ecological Demonstration Garden of fast-growing poplar plantations in northwestern Jiangsu. A significant difference in C concentration was observed among the poplar biomass components investigated (P ≤ 0.05), with the highest value in stemwood and the lowest in fine roots, ranging from 459.9 to 526.7 g kg−1. There was also a significant difference in C concentration among the different crop components (P ≤ 0.05), and the highest concentration was observed in the corn ear. Over the 5-year period, the total poplar biomass increased with increasing tree density, ranging from 8.77 to 15.12 t ha−1, while annual biomass production among the crops ranged from 4.69 to 16.58 t ha−1 in the three configurations. Overall, total C stock in the poplar intercropping system was affected by configurations and cropping systems, and configuration A obtained the largest total C stock, reaching 16.7 t C ha−1 for the wheat–soybean cropping system and 18.9 t C ha−1 for the wheat–corn cropping system. Results from this case study suggest that configuration A was a relative optimum poplar intercropping system both for economic benefits and for C sequestration.

Effect of Pod Sucking Bugs (Hemiptera: Coreidae, Alydidaei Infestation on Yield of Intercropped Cowpea (Vigna unguiculata (L.) Walp.] in Maiduguri, Nigeria.

An experiment was carried out at the University of Maiduguri Teaching and Research Farm to assess damage caused by pod sucking bugs [Anoplocnemis curvipes (Fab.), Cluvigralla shadabi Doll., C. tomentosicollis Stall, Riptortus dentipes (Fab.), Mirperusjaculus (Thun.), and Nezara viridula L.] on cowpea [Vigna unguiculata (L.) Walp.] between Jul. and Nov. 2002. Treatments were set up as 4x3x2 factorial arrangement in a strip-split design with planting date (Jul.3 1. Aug. 7. 14 and 21 ) as the main plot factor. cropping pattern of pearl millet [Pennisetum glaucutn (L.) R. Br.] and cowpea (3: 1: 2: 1: 1: 1) as subplot factor, and cropping system (millet-cowpea and millet-cowpea-soybean-groundnut intercrop) as sub-subplot factor. Results for planting date showed that the number of bugs/plant and percentage pod damage were significantly lower (P<0.05) while pod yield/plant was significantly higher for the cowpea planted on Jul. 31 compared with those planted on other dates. There were significantly (P<0.05) fewer numbers of bugs/plant for the 2: 1 cropping pattern, lower percentage pod damage for the I: 1 cropping pattern. and higher pod yield/plant for the 3: 1 cropping pattern. For the cropping system. millet-cowpea-groundnut-soybcan had lower number of bugs/plant and higher pod yield/plant than the millet-cowpea cropping system. Planting cowpea early in the season using the cropping pattern 3: 1 in conjunction with the millet-cowpea-groundnut soybean cropping system offered a more effective means of escaping from the yield-depressing effect of pod-sucking bug infestation.

Effect of monoculture soybean on soil microbial community in the Northeast China

Monoculture (MC) soybean, a common practice in the Northeast China, causes significant declines in soybean yield and quality. The objective of this study was to evaluate the responses of the soil microbial community and soybean yield to different soybean cropping systems. Three cropping systems were compared, (1) corn-soybean rotation (corn-corn-soybean, CS), (2) MC soybean for 3 years (S3), (3) MC soybean for 9 years (S9). Both bulk and rhizosphere soil samples were collected at three growth stages: two trifoliate (V2), full bloom (R2), and full seed (R6), respectively. Soil microbial DNA was analyzed using polymerase chain reaction (PCR)—denaturing gradient gel electrophoresis (DGGE) to assess changes in composition of bacterial and fungal communities. Prominent DGGE bands were excised and sequenced to gain insight into the identities of the predominant microbial populations. Some prominent differences were observed in bacterial DGGE patterns of amplified 16S rDNA (V3 region) among rhizosphere soils. These major differences included one DGGE band (showing 100% similarity to Arthrobacter sp.) that was enriched at R2 stages in CS and S9, and another band with 97% sequence similarity to an uncultured actinobacterium was detected at R6 stage in CS, and at R2 and R6 stages in S9. The bacterial community from bulk soil showed no significant band change in DGGE patterns among different cropping systems. In fungal DGGE patterns of the amplified 18S rDNA partial fragment, one specific band (showing 98% similarity to Trichoderma viride) occurred in rhizosphere soil of treatment CS at V2 and R6 stages and treatment S9 at R6 stage. None of the above bands were detected in treatment S3. The soybean yields and plant heights from CS and S9 were greater than those from S3. Moreover, catalase activities from CS and S9 at V2 and R2 stages were higher than those tested from S3 at the corresponding times in rhizosphere soil. The present results showed that DGGE patterns were not able to detect significant differences in diversity or evenness among microbial communities, but significant differences were found in the composition of bacterial and fungal community structures. Some distinguished bands from bacterial and fungal DGGE patterns were only enriched in CS and S9 soil, which could potentially play an important role in soybean growth development.

Phosphorus transformation in a soybean-cropping system in Andosol: effects of winter cover cropping and compost application

Understanding phosphorus (P) transformation is necessary to develop sustainable P management practices on Andosol with large P-fixing capacity. This study was conducted during 2005–2007 in northeastern Japan to determine how the amounts of inorganic P (Pi) and organic P (Po) fractions change in a Silandic Andosol under soybean production [Glycine max (L.)]. Two treatments were examined: application of composted cattle manure (0 (P0), 61 (P1), and 122 or 183 (P2) kg P ha−1 year−1) and winter cover cropping (no cover crop, rapeseed [Brassica napus], and cereal rye [Secale cereale L.]). Compost was applied before soybean seeding; cover crops were seeded after soybean harvest without further fertilization. Soil P was extracted sequentially with anion exchange resin (Pi), 0.5M NaHCO3 (Pi, Po), 0.1M NaOH (Pi, Po), and 0.5M H2SO4 (Pi). Soybean removed 42.3 and 48.5 kg P ha−1 (only 23 and 10% of the added P), respectively, in P1 and P2. In the P2 soil, 64% of excess P was distributed into Pi fractions, mainly resin-Pi and NaOH–Pi (29 and 19%, respectively). In P0, despite no P addition, soybean removed 41.5 kg P ha−1 concurrently with a decrease in NaOH–Pi, suggesting its potential contribution to soybean P uptake. Neither of cover crops had significant effect on soil P fractions during the 3 year period.

U.S. Grower Views on Problematic Weeds and Changes in Weed Pressure in Glyphosate-Resistant Corn, Cotton, and Soybean Cropping Systems

Corn and soybean growers in Illinois, Indiana, Iowa, Mississippi, Nebraska, and North Carolina, as well as cotton growers in Mississippi and North Carolina, were surveyed about their views on changes in problematic weeds and weed pressure in cropping systems based on a glyphosate-resistant (GR) crop. No growers using a GR cropping system for more than 5 yr reported heavy weed pressure. Over all cropping systems investigated (continuous GR soybean, continuous GR cotton, GR corn/GR soybean, GR soybean/non-GR crop, and GR corn/non-GR crop), 0 to 7% of survey respondents reported greater weed pressure after implementing rotations using GR crops, whereas 31 to 57% felt weed pressure was similar and 36 to 70% indicated that weed pressure was less. Pigweed, morningglory, johnsongrass, ragweed, foxtail, and velvetleaf were mentioned as their most problematic weeds, depending on the state and cropping system. Systems using GR crops improved weed management compared with the technologies used before the adoption of GR crops. However, the long-term success of managing problematic weeds in GR cropping systems will require the development of multifaceted integrated weed management programs that include glyphosate as well as other weed management tactics.

Organic manuring for soil biological health and productivity of a wheat - soybean cropping system in the Vertisols of central India

Soybean (Glycine max (L.) Merr.)–wheat (Triticum aestivum L.) is the dominant cropping system in the Vertisols of central India due to congenial climate, development of agro-industries, and export opportunities. Both are high-value crops, and raising them using organics may further improve produce quality and help in sustaining long-term productivity of the system. Information is lacking on how to sustain the system with the sole use of organics or biofertilisers in Vertisols. A long-term study was made during 1995–2002 at Indore, India, to evaluate the effectiveness of 3 organic manures [farmyard manure (FYM), poultry manure (PM) and vermicompost (VC) at varying rates] and biofertilisers (Azotobacter + phosphate solubilising bacteria) on productivity, grain quality, soil fertility, and profitability of a wheat–soybean cropping system. Grain yield of wheat was significantly increased with PM at 2.5–10 t/ha or FYM at 10–20 t/ha compared with the control. However, the highest productivity was obtained with PM at 10 t/ha, which even performed better than NPK, indicating that NPK fertilisers alone did not provide adequate and balanced nutrition for potential yield of the crop. Quality parameters of durum wheat, viz. protein content, hectolitre weight and sedimentation value, increased, while yellow berry content decreased significantly with PM at 2.5–10.0 t/ha compared with the control. Soybean yields were significantly influenced by the residual effect of organic manuring treatment applied to wheat. The treatment receiving PM at 10 t/ha produced the highest grain yield of wheat. However, this treatment could not produce a similar response in soybean yield due to production of excessive vegetative growth, adversely affecting grain yield. Superiority of PM over FYM, vermicompost and biofertilisers was evident in the overall profitability of the system. Various soil fertility parameters including chemical and biological properties showed conspicuous improvement over the initial status under the FYM and PM treatments. Microbial biomass C and activities of phosphatase and dehydrogenase were increased significantly with applications of manures. Sustainability yield index was maximum under PM at 5–10 t/ha, followed by NPK. Results suggested that application of PM at 5–10 t/ha to wheat was essential for improving productivity, grain quality, profitability, soil health, and sustainability of a wheat–soybean system.

Soil microbial communities under different soybean cropping systems: Characterization of microbial population dynamics, soil microbial activity, microbial biomass, and fatty acid profiles

This work analyzes the direct effect of soil management practices on soil microbial communities, which may affect soil productivity and sustainability. The experimental design consisted of two tillage treatments: reduced tillage (RT) and zero tillage (ZT), and three crop rotation treatments: continuous soybean (SS), corn–soybean (CS), and soybean–corn (SC). Soil samples were taken at soybean planting and harvest. The following quantifications were performed: soil microbial populations by soil dilution plate technique on selective and semi-selective culture media; microbial respiration and microbial biomass by chloroform fumigation-extraction; microbial activity by fluorescein diacetate hydrolysis; and fatty acid methyl ester (FAME) profiles. Soil chemical parameters were also quantified. Soil organic matter content was significantly lower in RT and SS sequence crops, whereas soil pH and total N were significantly higher in CS and SC sequence crops. Trichoderma and Gliocladium populations were lower under RTSS and ZTSS treatments. Except in a few cases, soil microbial respiration, biomass and activity were higher under zero tillage than under reduced tillage, both at planting and harvest sampling times. Multivariate analyses of FAMEs clearly separated both RT and ZT management practices at each sampling time; however, separation of sequence crops was less evident. In our experiments ZT treatment had highest proportion of 10Me 16:0, an actinomycetes biomarker, and 16:1ω9 and 18:1ω7, two fatty acids associated with organic matter content and substrate availability. In contrast, RT treatment had highest content of branched biomarkers (i15:0 and i16:0) and of cy19:0, fatty acids associated with cell stasis and/or stress. As cultural practices can influence soil microbial populations, it is important to analyze the effect that they produce on biological parameters, with the aim of conserving soil richness over time. Thus, in a soybean-based cropping system, appropriate crop management is necessary for a sustainable productivity without reducing soil quality.

Effect of glyphosate on the tripartite symbiosis formed by Glomus intraradices, Bradyrhizobium japonicum, and genetically modified soybean

Most soybeans grown in North America are genetically modified (GM) to tolerate applications of the broad-spectrum herbicide glyphosate; as a result, glyphosate is now extensively used in soybean cropping systems. Soybean roots form both arbuscular mycorrhizal (AM) and rhizobial symbioses. In addition to individually improving host plant fitness, these symbioses also interact to influence the functioning of each symbiosis, thereby establishing a tripartite symbiosis. The objectives of this study were to (1) estimate the effects of glyphosate on the establishment and functioning of AM and rhizobial symbioses with GM soybean, and (2) to estimate the interdependence of the symbioses in determining the response of each symbiosis to glyphosate. These objectives were addressed in two experiments; the first investigated the importance of the timing of glyphosate application in determining the responses of the symbionts and the second varied the rate of glyphosate application. Glyphosate applied at recommended field rates had no effect on Glomus intraradices or Bradyrhizobium japonicum colonization of soybean roots, or on soybean foliar tissue [P]. N 2-fixation was greater for glyphosate-treated soybean plants than for untreated-plants in both experiments, but only when glyphosate was applied at the first trifoliate soybean growth stage. These data deviate from previous studies estimating the effect of glyphosate on the rhizobial symbiosis, some of which observed negative effects on rhizobial colonization and/or N 2-fixation. We did observe evidence of the response of one symbiont (stimulation of N 2-fixation following glyphosate) being dependent on co-inoculation with the other; however, this interactive response appeared to be contextually dependent as it was not consistent between experiments. Future research needs to consider the role of environmental factors and other biota when evaluating rhizobial responses to herbicide applications.

Sugarcane Response to Mill Mud, Fertilizer, and Soybean Nutrient Sources on a Sandy Soil

Improving soil organic matter and soil fertility are important factors in the sustainability of sugarcane (Saccharum spp.) production. A 3‐yr field trial was established in 2004 on a sandy Alfisol in Florida to compare the effect of organic and inorganic nutrient sources on sugarcane production. The three nutrient sources were (i) mill mud (filter cake, cachaza), (ii) local standard fertilizer, and (iii) soybean cropping system before sugarcane. Soybean green manure increased sucrose yield (TSH, t sucrose ha−1) 20% in plant cane, however when aboveground biomass was removed soybean rotation did not improve sugarcane yields. Fertilization did not increase yields if mill mud was added to plant cane. Soybean green manure did not improve sugarcane ratoon crop yields, and there were no significant interactions in the ratoon crops. The application of mill mud resulted in a 49% TSH increase in first ratoon and a 167% increase in second ratoon whereas inorganic fertilizer application increased TSH by 31 and 49% in first and second ratoon, respectively. Over the 3‐yr crop cycle, addition of mill mud alone led to an increase of 4.1 TSH compared with inorganic fertilizer alone, whereas soybean green manure alone produced 2.6 TSH less than fertilizer. However, combinations of nutrient sources with mill mud had additive effects in the ratoon crops. Our results indicate that mill mud was more effective than soybean green manure or local standard fertilizer practices in increasing sugarcane yields on sand. However, growers should fertilize ratoon crops when mill mud has been applied to achieve maximum sugarcane yields.

Effect of rotation crops on hatch, viability and development of Heterodera glycines

AbstractRotation with non-host crops can be an effective method for reducing soybean cyst nematode (Heterodera glycines) populations in soybean cropping systems. Sunn hemp, Illinois bundleflower, oilseed rape, perennial ryegrass, red clover, corn and H. glycines-susceptible soybean were compared for their effects on H. glycines hatch, viability and development in laboratory and glasshouse experiments. In the laboratory experiments, root exudates in soil leachates, extracts from fresh plant tissues, and extracts from residues of sunn hemp, red clover and soybean stimulated hatch of second-stage juveniles (J2) of H. glycines. All crops appeared to contain hatch inhibitors as well. There was no apparent effect of the root exudates and extracts from any of the crops on egg viability in vitro. When the H. glycines J2 were exposed to root exudates and extracts for 72 h, only the extracts of fresh plants and plant residue from sunn hemp, red clover and soybean, and the extract of plant residue from oilseed rape reduced viability of J2. In glasshouse experiments, residues of all crops, except Illinois bundleflower, reduced egg population density, with sunn hemp providing the greatest reduction. Residues of sunn hemp, red clover, and perennial ryegrass added to soil reduced the reproduction factor, suggesting the residues not only reduced egg population density but also reduced nematode infectivity. While all crops allowed penetration by J2, minimal development (to third- or fourth-stage juveniles only) occurred only in sunn hemp, red clover, oilseed rape and Illinois bundleflower, and full development occurred only in soybean. The results suggest that sunn hemp and red clover were the most effective rotation crops for managing H. glycines, and that stimulating hatch of H. glycines J2 was the main mechanism involved in reducing the H. glycines population density.

Sustaining productivity of wheat–soybean cropping system through integrated nutrient management practices on the Vertisols of central India

Wheat–soybean is one of the most dominant cropping systems on the Vertisols of central India. Cultivation of durum wheat in winter season (November to April) has a considerable potential due to congenial climate, while soybean in rainy season (June to October) has witnessed a phenomenal growth in the last two decades in the region. Beside including a legume (soybean) in sequence with a cereal crop (wheat), combined use of available organic sources along with chemical fertilizers may prove beneficial for long-term productivity and sustainability of the system. A long-term experiment was conducted during 1995–2000 on the fine-textured Vertisols at Indore, India to study the effect of combined use of farmyard manure (FYM), poultry manure, vermicompost and biofertilizers (Azotobacter + phosphate solubilizing bacteria) with 0.5 and 1.0 NPK (120 kg N + 26.2 kg P + 33.3 kg K ha−1) on wheat, and residual effect on following soybean. Grain yield of aestivum wheat in the initial 2 years and durum wheat in the later 3 years was significantly increased with 0.5 NPK + poultry manure at 2.5 t ha−1 or FYM at 10 t ha−1 compared with 0.5 NPK alone, and was on par with 1.0 NPK. However, the highest productivity was obtained when these organic sources were applied along with 1.0 NPK. Quality parameters of durum wheat viz protein content, hectolitre weight and sedimentation value showed improvement, and yellow berry content was significantly lower with combined use of NPK + organic sources compared with NPK alone and control. Soybean did not show much response to residual effect of nutrient management treatments applied to wheat. Wheat gave higher profit than soybean, particularly in the later years due to lower grain yields and market price of soybean. However, the superiority of FYM as well as poultry manure along with 1.0 NPK was evident on the overall profitability of the system. Various soil fertility parameters including chemical and biological properties showed conspicuous improvement over the initial status under the treatments of FYM and poultry manure. Sustainability yield index was maximum under 1.0 NPK, followed by 1.0 NPK + poultry manure or FYM. It was concluded that application of available organic sources, particularly FYM and poultry manure along with full recommended dose of NPK fertilizers to wheat was essential for improving productivity, grain quality, profitability, soil health and sustainability of wheat–soybean system.

Glyphosate Application Timing and Rate for Annual Ryegrass (Lolium Multiflorum) Cover Crop Desiccation

Annual ryegrass has been proposed as a cover crop in the corn–soybean cropping systems of the U.S. Midwest because of its low seed cost, rapid establishment, contribution to soil quality, weed suppressive abilities, and susceptibility to common broad-spectrum herbicides. However, cover crops can reduce the subsequent main crop yield by creating unfavorable germination and emergence conditions, harboring pests, and if not controlled, competing with the main crop. This study, conducted in Illinois, Oregon, and Tennessee, investigated the efficacy of glyphosate for annual ryegrass winter cover crop removal. Glyphosate at 415, 830, and 1,660 g ae/ha was applied to annual ryegrass at late tiller, second node, boot, and early flowering stages. Annual ryegrass control was consistently maximized with the highest glyphosate rate applied at the boot or early flower stage. Annual ryegrass biomass was generally the lowest with the highest rate of glyphosate applied at the earlier stages. Overall, no single application timing at any glyphosate rate provided complete control or biomass reduction of the annual ryegrass cover crop. A sequential herbicide program or a glyphosate plus a graminicide tank-mix probably will be needed for adequate annual ryegrass stand removal. Nomenclature: Glyphosate; annual ryegrass Lolium multiflorum L. LOLMU; corn, Zea mays L.; soybean, Glycine max (L.) Merr.

Ácaros associados à cultura da soja no Rio Grande do Sul

During the last growing seasons, high infestations of phytophagous mites were observed in the State of Rio Grande do Sul, Brazil, becoming necessary to apply pesticides for their control. The objective of this study was to identify phytophagous and predatory mite species associated with soybean in ten counties of that state, during the 2002/03 and 2003/04 growing seasons, in five soybean cultivars (A 6001 RG, A 7001 RG, A 8000 RG, A 8100 RG, Anta 82), all genetically modified. In samples of soybean leaves four phytophagous mite species (Mononychellus planki (McGregor), Polyphagotarsonemus latus (Banks), Tetranychus desertorum Banks and Tetranychus gigas Pritchard & Baker) and two predatory mite species (Phytoseiulus fragariae Denmark & Schicha and Typhlodromalus aripo De Leon) were found. T. desertorum was found for the first time associated with soybean in the country. Phytoseiulus fragariae and T. aripo are reported for the first time on soybean. The potential of phytoseid mites as biological control agents in soybean crop was discussed. Among the hypotheses to explain the increasing infestation of soybean fields with phytophagous mites area are the progressively larger cultivated area, the dry spells observed in the last few years in the growing season, changes in soybean cropping system that led to increased use of pesticides and utilization of new soybean cultivars with morphological or biochemicals characteristics that favour the development of these mite populations.

Planting date effects on the germinability and seedling vigour of Abutilon theophrasti (Malvaceae) seeds

Abutilon theophrasti (Malvaceae) is a troublesome annual weed in many maize and soybean cropping systems of Canada and the United States. Seeds of A. theophrasti exhibit physical dormancy. Differences in the growing environment of parent plants may influence the germinability of seeds and vigour of seedlings produced by this species because of variation in resource allocation to seed development. Thus, the germinability of seeds and subsequent seedling vigour were examined for A. theophrasti plants grown in monoculture at a density of 4.2 plants m-2 under varying natural photoperiods in central New York State. Treatments were established by transplanting A. theophrasti seedlings on three dates: 15 May, 4 June, and 30 June 2000, which correspond to peak photoperiods of 15, 14, and 13 hours, respectively. Seeds produced under the shorter photoperiod (13 h) weighed, on average, 1.5 mg less than seeds produced under the longer photoperiod (15 h). Contrary to expectations, seeds of A. theophrasti that matured under shorter photoperiods had lower germinability (80%) than seeds produced under longer photoperiods (98%). Early radicle growth, a measure of seedling vigour, did not differ between the photoperiod treatments. Environmental conditions other than photoperiod (i.e. water availability) prevailing during the 2000-growing season may have influenced seed coat thickness and consequently affected the germinability of seeds.