Soybean Row Research Articles

Relationships among light distribution, radiation use efficiency and land equivalent ratio in maize-soybean strip intercropping

Maize (Zea mays)-soybean (Glycine max) intercropping is popular in many developing countries because of its high land equivalent ratio (LER). However, very few studies have explored the reason of its high LER, and the relationships between light distribution and the variations in radiation use efficiency (RUE) and LER in different intercropping arrangements. In this study, we conducted field experiments with different row arrangements of intercropping patterns from 2013 to 2015. The three different strip intercropping (SI) row arrangements were 0.2 m, 0.4 m, and 0.7 m (SI1); 0.4 m, 0.4 m, and 0.6 m (SI2); and 0.6 m, 0.4 m, and 0.5 m (SI3) for maize row distance, soybean row distance, distance between maize and soybean rows, respectively. The results showed that, as compared to single row intercropping, the strip intercropping increased the PAR at top of soybean canopy by 1.42 (SI3), 1.67 (SI2) and 1.93 (SI1) times, and increased the PAR at maize leaves close to the ear by 1.02 (SI3), 1.11 (SI2) and 1.12 (SI1) times. Moreover, the increased PAR at crucial positions in SI potentially improved the photosynthetic rate (Pn) for maize leaves close to the ear and radiation use efficiency (RUE) of maize by 1.08 and 1.09 times (averaged by SI1, SI2 and SI3), respectively, and improved the Pn of leaves at top of canopy and intercepted PAR of soybean by 1.75 and 1.36 times (averaged by SI1, SI2 and SI3), respectively. Compared to monoculture, SI also enhanced the RUE of intercropped maize (by 1.18 times) and soybean (by 1.51 times), which compensated for the partial yield loss caused by decreased crop intercepted PAR. Overall, in SI, intercropped maize achieved 90% of the monoculture yield, and intercropped soybean achieved 47% of the monoculture yield. With the expanding gap width for growing soybeans under a fixed bandwidth (2 m), the increasing intercepted PAR of intercropped soybean alleviated the interspecific competition disadvantage of soybean, while the reduction of maize row width decreased the dominant interspecific competition of maize. By adjusting the distances, we suggest that the optimal gap width for growing soybeans is 1.6 m-1.8 m, and the best maize row distance is 0.4 m. The SI2 achieved LER of 1.42, representing the leading level in the world.

Determining in-field dispersal of the redbanded stink bug (Hemiptera: Pentatomidae) in soybean fields using a protein based mark-capture method

A study was designed to determine the dispersal of redbanded stink bug, Piezodorus guildinii (Westwood), adult and nymph in soybean fields using protein marking via a mark-captured method. Insects were marked by spraying the soybean field with 10% chicken egg white solution. Following marker application, insects were collected from the field. Marker on the insect body was detected using chicken egg albumin specific indirect enzyme-linked immunosorbent assay (ELISA) to assess dispersal of P. guildinii. The protein marking was found to be a viable option for marking P. guildinii that provided direct proof of insect movement. With this marking technique, we were able to detect 50% or more protein marked insects for 3 days after field marking, however marker was detected in 50% or more soybean leaf sample only for 2 days after field marking. Marking efficiency drastically reduced after 4–5 days of marker application in the soybean field. Thus, the method, though useable, has limitations. Mean dispersed distance of P. guildinii was up to 137.0 ± 21.5 m along soybean rows and 15.3 ± 1.2 m across rows. Mean nymphal dispersal (4th and 5th instars) was documented up to 122.0 ± 7.0 m along and 11.7 ± 1.7 m across soybean rows.

Chemical compositions of essential oil and antioxidant activity of dragonhead (Dracocephalum moldavica) in sole crop and dragonhead- soybean (Glycine max) intercropping system under organic manure and chemical fertilizers

Organic manure can be used as an alternative for chemical fertilizers in sustainable agriculture. In addition, compared with sole cropping systems, intercropping is a promising approach for the crop production due to its lower reliance to chemical fertilizers. In this study, grain yield of soybean and biomass, chemical compositions and antioxidant activity of dragonhead essential oil in sole crop and dragonhead-soybean intercropping system under organic and chemical fertilizers were investigated. Land equivalent ratio (LER) was calculated as well. Results indicated intercropping and application of organic manure, increased soybean grain yield and dragonhead biomass. The LER value for soybean: dragonhead with ratios of 1:1 and1:2 under organic manure was greater than 1, indicating superiority of intercropping versus sol crop systems. GC–MS analysis showed that geranial, geranyl acetate, neral and piperitone were major compounds of dragonhead. The geranial and neral contents were increased in sole cropped dragonhead with application of chemical fertilizer, while the piperitone content was enhanced in sole cropped plants fertilized with organic manure. The highest of geranyl acetate content was observed in intercropped dragonhead plants fertilized with chemical fertilizer. Addition of organic manure lead to increase the antioxidant capacity of dragonhead in intercropped plots. The highest antioxidant activity of dragonhead (IC50 = 1.45 μgmL−1) was observed in one row of soybean + two rows of dragohead treated with organic manure. Overall, one row of soybean + two rows of dragohead with use of organic manure was more productive and had the highest LER value, antioxidant activity and a large amount of chemical compositions of essential oil. Thus this treatment could be adopted by the medicinal plant growers for appropriate production of dragonhead.

Evaluating different interrow distance between corn and soybean for optimum growth, production and nutritive value of intercropped forages

BackgroundMaize fodder is being used as staple feed for livestock but it lacks protein and essential amino acids; lysine and tryptophan. Intercropping maize with leguminous soybean crop is promising technique under limited land resources of South Korea but it can only give considerable advantages when adequate distance is provided between corn and soybean rows. Main aim of present study was to find-out adequate distance between corn and soybean seeding rows for optimum growth, yield and nutritive value of intercropped forage.MethodsDifferent interrow distances between corn and soybean were evaluated under four treatments, viz. 1) Corn sole as positive control treatment 2) Zero cm between corn and soybean (control); 2) Five cm between corn and soybean; 3) 10 cm between corn and soybean, with three replicates under randomized block design.ResultsFindings depicted that height and number of corn stalks and ears were similar (P > 0.05) among different treatments. Numerically average corn ear height was decreased at zero cm distance. Dry matter percentage in all components; corn stalk, corn ear and soybean was also found not different (P > 0.05) but dry matter yield in component of corn ear was lower (P < 0.05) at zero cm distance as compared to that of 5 and 10 cm interrow distances. In case of nutritive value, total digestible nutrient yield in intercropped corn was also found lower (P < 0.05) at zero cm distance than that of 5 and 10 cm interrow distances between corn and soybean seeding rows. Substantial decrease in dry matter yield of maize ear at zero cm distance might be attributed to factor of closed interrow spacing which made interplant competition more intensified for light interception, necessary for photosynthetic activity. Lower dry matter yield in ear also reduced total digestible nutrients in intercropped maize because it was determining factor in calculation of digestible nutrients. The optimum yield and nutritive value of forage at wider interrow distance i.e. 5 cm between corn and soybean might be due to adequate interseed distance.ConclusionConclusively, pattern of corn and soybean seeding in rows at 5 cm distance was found suitable which provided adequate interrow distance to maintain enough mutual cooperation and decreased competition between both species for optimum production performance and nutritive value of intercropped forage.

Weed infestation and productivity of maize/soybean intercrop as influenced by cropping patterns in the southern Guinea savanna of Nigeria

Field experiments were conducted during the 2015 and 2016 cropping seasons at the Teaching and Research (T &amp; R) Farm of the College of Agriculture, Kwara State University, Malete, to determine the effect of cropping patterns on weed infestation, growth and yield of a maize/soybean intercrop in the southern Guinea savanna of Nigeria. The experiments consisted of six treatments as follows: one row of maize alternated with one row of soybean (1:1), one row of maize alternated with two rows of soybean (1:2), two rows of maize alternated with one row of soybean (2:1), two rows of maize alternated with two rows of soybean (2:2), sole maize (1:0) and sole soybean (0:1). The treatments were laid out in a randomized complete block design with three replicates. Data collected were subjected to analysis of variance and means were separated by the least significant difference (LSD) at the 5% level of probability. Results showed that sole soybean consistently suppressed weeds and resulted in a higher yield. Similarly, the 2:1 ratio of maize to soybean did not only reduce weed density, it produced significantly higher yields of maize and lower yield of soybean, and had the higher land equivalent ratio and economic returns followed by sole maize.

Spacing between Soybean Rows

The soybean crop has great economical importance in Brazil and in the world. In order to make the crop production profitable, several factors must be considered. The objective of this study was to evaluate the impact of spacing between soybean crop rows (Glycine max). The experiment was installed in the Mutuca farm (Arapoti—PR, southern Brazil), in the crop seasons of 2012/2013 (four seeding seasons) and 2013/2014 (two seeding seasons), in a completely randomized blocks design. We used four treatments and six replicates. The treatments were the spacing between rows as follow: 0.25, 0.50, 0.75 and 1.00 m. The variables evaluated were: initial and final plant population, plant height, number of internodes, viable internodes, pods per plant, grains per pod, mass of thousand grains and crop productivity. We concluded that the reduction of the spacing between rows significantly increased, in most part of the crop seasons, the number of pods per plants and the crop productivity.

Effects of Maize-Soybean Intercropping on Nitrous Oxide Emissions from a Silt Loam Soil in the North China Plain

Maize (Zea mays L.), a staple crop in the North China Plain, contributing substantially to agricultural nitrous oxide (N2O) emissions in this region. Many studies have focused on various agricultural management measures to reduce N2O emissions. However, few have investigated soil N2O emissions in intercropping systems. In the current study, we investigate whether maize-soybean intercropping treatments could reduce N2O emission rates. Two differently configured maize-soybean intercropping treatments, 2:2 intercropping (two rows of maize and two rows of soybean, 2M2S) and 2:1 intercropping (two rows of maize and one row of soybean, 2M1S), and monocultured maize (M) and soybean (S) treatments were performed using a static chamber method. The results showed no distinct yield advantage for the intercropping systems. The total N2O production from the various treatments was 0.15 ± 0.04–113.85 ± 12.75 µg m−2 min−1. The cumulative N2O emission from the M treatment was 16.9 ± 2.3 kg ha−1 over the entire growing season (three and a half months), which was significantly higher (P < 0.05) than that of the 2M2S and 2M1S treatments by 36.6% and 32.2%, respectively. Two applications of nitrogen (N) fertilizer (as urea) at 240 kg N ha−1 each induced considerable soil N2O fluxes. Short-term N2O emissions (within one week after each of the two N applications) accounted for 74.4%–83.3% of the total emissions. Soil moisture, temperature, and inorganic N were significantly correlated with soil N2O emissions (R2 = 0.246–0.365, n = 192, P < 0.001). Soil nitrate (NO−)3 and moisture decreased in the intercropping treatments during the growing season. These results indicate that maize-soybean intercropping can reduce soil N2O emissions relative to monocultured maize.

Estimating soil carbon dynamics in intercrop and sole crop agroecosystems using the Century model

AbstractUsing process‐based models to predict changes in carbon (C) stocks enhances our knowledge on the long‐term dynamics of soil organic carbon (SOC) in various land management systems. The objective of this study was to apply the Century model to evaluate temporal SOC dynamics in two temperate intercrop systems [1:2 (one row of maize and two rows of soybeans); 2:3 intercrop (two rows of maize and three rows of soybean)] and in a maize and soybean sole crop. Upon initiation of intercropping, SOC increased by 47% after ≈ 100 years, whereas SOC in the maize sole crop increased by 21% and 2% in the soybean sole crop. The quantity of crop residue input was sufficient to increase the active (turnover time of months to years) SOC fraction in the intercrops and the maize sole crop, but not in the soybean sole crop. The slow fraction, with a turnover time of 20 to 50 years, increased in all crop systems and was the major driver of SOC accumulation. A 3 to 15% loss of SOC from the passive fraction, with a turnover time of 400 to 2000 years, in all crop systems showed the long‐term impact of land‐use conversion from historically undisturbed native grasslands to intensive agricultural production systems. This study provided an example of the potential of process‐based models like Century to illustrate possible effects of cereal–legume intercropping on SOC dynamics and that the model was able to predict SOC stocks within –7 to +4% of measured values. We conclude, however that further fine‐tuning of the model for application to cereal–legume intercrop systems is required in order to strengthen the relationship between measured and simulated values.

Effects of Different Planting Pattern of Maize (&amp;lt;i&amp;gt;Zea mays&amp;lt;/i&amp;gt; L.) and Soybean (&amp;lt;i&amp;gt;Glycine max&amp;lt;/i&amp;gt; (L.) Merrill) Intercropping in Resource Consumption on Fodder Yield, and Silage Quality

An experiment was carried out at the field units of the north campus experimental areas in Northwest Agriculture and Forestry University, Yangling, Shaanxi Province, P. R. China. The experiment was conducted on summer season (June to September) to determine the effects of different planting patterns of maize and soybean intercropping in resource consumption on fodder yield and silage quality. The main treatments were one sole crop of maize (SM) and four maize-soybean intercropping patterns (1 row maize to 1 row soybean (1M1S), 1 row maize to 2 rows soybean (1M2S), 1 rows maize to 3 rows soybean (1M3S) and 2 rows maize to 1 row soybean (2M1S), respectively. The experiment was a randomized complete block design with three replications, and plot size of 12 m by 5 m. The crops were harvested when the maize reached at milk stage and soybean at R7 stage. The result indicated significant increase in fresh biomass and dry matter production of maize fodder alone as compared to maize intercropped with soybean fodder. It was correlated with a higher consumption of environmental resources, such as photosynthetically active radiation (PAR) and soil moisture by intercropping. After 45 days of ensiling period, silage samples were analyzed for pH, organic acids (Lactic, acetic, and butyric), dry matter (DM), crude protein (CP), ether extract (EE), neutral detergent fibre (NDF), acid detergent fibre (ADF), calcium (Ca), sodium (Na), phosphorus (P), magnesium (Mg), and potassium (K). It was concluded that in all intercropped silages, crude protein (CP) values were higher (1M1S, 12.1%; 1M2S, 12.2%; 1M3S, 12.4%; 2M1S, 12.1%) than the monocrop maize (SM, 8.7%) silage. Higher organic acids (p < 0.05) were produced in the 1M3S silages as compared to others silages. The study indicated that among all intercropped silages, the 1M3S (1 row maize to 3 rows soybean) was preferable according to nutrient composition than other intercropped silages.

Influence of spatial arrangement in maize-soybean intercropping on root growth and water use efficiency

The relationship between transpiration and root distribution under different spatial arrangements of intercropping is poorly understood. The effects of three spatial arrangements in the maize (Zea mays L.) - soybean (Glycine max L.) intercropping on root distribution, transpiration, water use efficiency (WUE) and grain yield were examined. Two-year field experiments were conducted using three spatial arrangements of 2 rows maize × 4 rows soybean (M2S4), 2 rows maize × 2 rows soybean (M2S2) and 4 rows maize × 2 rows soybean (M4S2), with their respective sole crops (monocrop) for comparison. The grain yield of maize in intercrops was higher than its monocrop and that of soybean in intercrops was lower than its monocrop. Except for M2S2 in 2014, there were yield advantages in intercropping due to improvement in the land use efficiency. Transpiration in maize was higher than in soybean regardless of the spatial arrangements. Transpiration of both maize and soybean was influenced by the spatial arrangements of the intercropping with M4S2 or M2S4 tending to have higher daily transpiration than monocrops and other spatial arrangements. Intercropping enhanced root length density (RLD) in both maize and soybean compared to the corresponding monocrop. RLD was higher and land equivalent ratio (LER) was lower under M2S2 than under other spatial arrangements of intercropping, WUE was higher in M4S2 than in other spatial arrangements. Intercropping was more efficient in using the environmental resources than monocropping. The M4S2 spatial arrangement in the maize-soybean intercropping could be selected because of its sustainability and greater land and water use efficiency.

Effect of aboveground and belowground interactions on the intercrop yields in maize-soybean relay intercropping systems

Aboveground and belowground interactions are crucial in the over-yielding of intercropping systems. However, the relative effects of aboveground and belowground interactions on yields of intercrops in maize (Zea mays L.) and soybean [Glycine max (L.) Merr.] relay intercropping systems are still unclear. Field experiments, including measurements of biomass, grain yield, and photosynthetic parameters, were conducted in 2013–2014 to analyze the advantages and effects of aboveground and belowground of interspecies interactions on yield. To analyze the aboveground interactions of intercrops for light interception, this study adopted three different row configurations [(P1) “160cm+40cm” and (P2) “120cm+80cm” maize wide-narrow row planting, where two rows of soybean with a 40-cm row width were planted in the wide rows, and (P3) “100cm +100cm” maize equal-row planting, where one row of maize and one row of soybean with a 50-cm spacing between the adjacent rows of both crops]. Moreover, to identify interspecies belowground competition, no root separation (R1) and root separation (R2) were employed between adjacent maize and soybean rows.The photosynthetically active radiation (PAR) transmittances of maize wide-row were significantly higher than those of maize narrow-row at the sixth leaf stage (jointing stage), twelfth leaf stage (bell stage), and tasseling stage. Specifically, PAR transmittances decreased as maize narrow-row spacing increased. No significant differences in the PAR transmittances of maize narrow-row or wide-row were found between the R1 and R2 conditions. Similarly, no significant differences between intercrop biomass and grain yield were observed between the R1 and R2 conditions. By contrast, different row configuration treatments exhibited significant differences in biomass (whole growth period for soybean and after tasseling stage for maize), grain yield and photosynthetic parameters of intercrops. These results implied that aboveground interactions, such as mutual shading, have more significant contributions to intercrop advantages than belowground interactions. In addition, the intercropped maize yields increased as maize narrow-row spacing (from P1 to P3 treatment) increased. However, contrasting trends were found for intercropped soybean yield and land equivalent ration (LER). No significant differences in LER were observed between R1 and R2 conditions in different row configurations. P1 treatment exhibited the maximum LER (1.64 for 2013 and 1.83 for 2014) and mixed yield (7430kgha−1 for 2013 and 9559kgha−1 for 2014), but the lower maize yield compared with P2 and P3 treatments. This result suggested that reducing the competitive ability of maize while increasing that of soybean significantly improves intercropping advantage in maize-soybean relay intercropping systems.

Impact of residue addition on soil nitrogen dynamics in intercrop and sole crop agroecosystems

Soil nitrogen (N) is one of the most important nutrients for plant productivity and microbial activity in terrestrial ecosystems. However, soil N is also readily affected by land management practices, influencing N2O emissions. This study assessed N dynamics in soil from different crop systems including a 1:2 (one row of maize and two rows soybean) and 2:3 (two rows of maize and three rows of soybean) intercrop and a maize and soybean sole crop as a result of residue addition from maize or soybeans. This was achieved through a 140-day incubation study using δ15N natural abundance. The effect of residue addition on soil TN was greater than its influence on crop systems when compared to treatments with no residue addition (Cont). The influence of residue addition on intercrops was most readily observed in the fractionated soil. Light fraction N (LF-N) and soil microbial biomass N (SMB-N) were significantly greater (p<0.05) in the intercrops than in the sole crops. Residue amended treatments were significantly (p<0.05) depleted in δ15N-TN, δ15N-LF and δ15N-SMB compared to Cont treatments. The δ15N-SMB was significantly enriched (p<0.05) compared to that of the residue, TN and LF-N. Residue amended treatments had significantly lower (p<0.05) N2O emissions than Cont treatments. However, N2O emissions were not significantly different (p<0.05) between soybean and maize amended treatments, nor between intercrops and sole crops. Our results demonstrate that the addition of contrasting residue types influenced short-term N dynamics in intercrops differently than sole crops.

Sequestration of native soil organic carbon and residue carbon in complex agroecosystems

ABSTRACTKnowing short-term gains and losses of soil organic carbon (SOC) is crucial for understanding the role of different land management practices in climate change mitigation. This study evaluated the flow of carbon (C) in soil from two differently configured intercrops [1:2 (one row of maize and two rows soybean); 2:3 (two rows of maize and three rows of soybean)] compared to a maize and soybean sole crop as a result of residue addition. Addition of soybean or maize residues significantly increased (p < 0.05) SOC, light fraction (LF-C), and soil microbial biomass (SMB). Soil organic C from native sources was significantly greater (p < 0.05) than C from new (residue) sources. The LF had a significantly greater (p < 0.05) C content from new sources. Treatments amended with soybean residue had a significantly greater (p < 0.05) contribution from new C sources for SOC and LF than treatments amended with maize residue. The SMB-C was significantly greater (p < 0.05) in the 2:3 intercrop. Cumulative soil CO2 emission was significantly lower (p < 0.05) in intercrops than in sole crops. CO2 emissions derived from new C sources was significantly greater (p < 0.05) than that derived from native sources in maize amended treatments; and not significantly different (p < 0.05) for treatments amended with soybean residues.

Changes in light environment, morphology, growth and yield of soybean in maize-soybean intercropping systems

The maize-soybean intercropping system has become increasingly popular in many areas of the world, particularly in China, due to its high productivity and the harvest of two different grains. While efforts have been made to maintain the yield of the taller maize crop, there is limited understanding of how the morphology, growth and yield of the lower soybean crop changes in response to the shading by maize. We therefore conducted a three-year field experiment from 2013 to 2015 to investigate the changes in light environment, growth of individual organs, biomass, and grain yield of soybean under two intercropping patterns (1M1S, one row of maize with one row of soybean; 2M2S, two rows of maize with two rows of soybean) as compared to monoculture. Our results showed that at soybean flowering stage, the R:FR ratio at the top of soybean canopy was reduced 17–21% more than the photosynthetically active radiation (PAR) under intercropping compared to monoculture, with 15–19% more reduction under 1M1S than 2M2S. This led to increased internode lengths, plant height and specific leaf area (SLA), but reduced branching of soybean plants under intercropping. These morphological changes enabled the crop to intercept relatively more light and the shading also increased the light use efficiency (LUE) of soybean. However, these positive responses were not able to compensate the effect of reduced leaf area (due to smaller leaf size and less branching) and total light interception, leading to reduced biomass and grain. The reduction in grain yield was mainly caused by the reduced number of grains (particularly on the middle nodes) produced by the intercropped soybean plants, while the grain size remained unchanged. The data and results of this study may be used to develop and parameterize crop models for simulating development and growth of soybean crop in response to changes in the light environment under intercropping.

Effect of narrow-row planting patterns on crop competitive and economic advantage in maize–soybean relay strip intercropping system

Narrow-row planting patterns directly affect crop yield and competition in intercropping systems. A two-year (2012 and 2013) field experiment was conducted to determine the interactive behavior between intercrops in a maize–soybean relay strip intercropping system. Maize plants were planted in different narrow-wide row planting patterns, whereas soybean was planted in wide rows. The total biomass and grain yield of maize increased with increasing maize narrow-row spacing, but the opposite trend was observed for soybean. The aggressivity, competitive ratio, and partial relative crowding advantage values for maize were greater than those for soybean. Moreover, the competitive interaction of the intercrops was affected by the distance between maize and soybean rows. The highest intercrop land equivalent ratio (LER) 1.61 and 1.59 was found in the 40:160 planting pattern (i.e. 40 cm narrow-row spacing and 160 cm wide-row spacing of maize) during 2012 and 2013, respectively. Combined with actual yield loss and LER, the intense intra-specific competition of maize plants reduced the depression for the associated soybeans when the maize narrow-row spacing was less than 30 cm. When the narrow-row spacing was wider than 50 cm, soybean growth was seriously depressed by maize because of the stronger inter-specific competition between maize and soybean. The maximum yield and economic advantage appeared in the 40:160 narrow-wide row planting pattern. Therefore, intercropping advantage may be achieved by changing the row spacing and distance between intercrop rows to coordinate the inter-specific competition between maize and soybean.

Effects of reduced nitrogen input on productivity and N 2 O emissions in a sugarcane/soybean intercropping system

A seven-year (2009–2015) continuous field experiment was established at the South China Agricultural University in order to identify the effects of sugarcane/soybean intercropping and reduced N rate on ecosystem productivity, yield stability, soil fertility, and N2O emissions. The randomized block experiment was designed with four cropping patterns (sugarcane monocropping (MS), soybean monocropping (MB), sugarcane/soybean (1:1) intercropping (SB1), and sugarcane/soybean (1:2) intercropping (SB2)) and two rates of N fertilization (300 kg hm−2 (N1, reduced rate) and 525 kg hm−2 (N2, conventional rate)). The results showed that the land equivalent ratio (LER) of all intercropping systems was greater than 1 (between 1.10 and 1.84), and the SB2-N1 optimally improved the land utilization rate among all treatments. The cropping patterns and N applied rates had no significant effect on sugarcane yield. The soybean yield was influenced by different cropping patterns because of different planting densities (4, 8 and 16 rows of soybean were plant under SB1, SB2, and MB, respectively) and was adopted in this experiment. In addition, under the SB2 cropping pattern, the soybean yield at the reduced N application rate was higher than that at the conventional N application rate. Wricke’s ecovalence (Wi2), the sustainable yield index (SYI) and the coefficient of variation (CV) were used to evaluate yield stability. Different treatments had no significant effects on sugarcane yield stability, as demonstrated by three indicators (Wi2, SYI and CV), which indicated that intercropping with soybean and reduced N rate had no effect on sugarcane yield. For soybeans, the value of Wi2 demonstrated that the stability of the intercropping system was higher than its counterpart monocropping system, as SYI and CV values indicated that SB2 had higher stability than SB1. During seven years of experiments, there was no significant difference in the soil fertility between MS and SB patterns. The soybean monocropping had a higher available K, pH and lower available P content than sugarcane inter- and mono-cropping. Different cropping patterns had a slight impact on N2O emissions and the greenhouse gas intensity (GHGI) value. Higher N input promoted N2O emissions and increased GHGI values. In conclusion, the present study observed that a 40% reduced nitrogen input combined with intercropping soybeans could maintain sugarcane yield and soil sustainable utilization, and that higher N fertilizer additions induced negative impacts on greenhouse gases emissions. Sugarcane intercropping with soybeans can reduce chemical fertilizer input and simultaneously maintain crop productivity; thus, it can be considered to be a reasonable practice for field management.

Effect of Different Planting Structure of Maize and Soybean Intercropping on Fodder Production and Silage Quality

A study was conducted to examine the effects of different planting structure of maize (Zea maysL.) and soybean (Glycine max L.) intercropping on fodder production and silage quality.Maize was cultivated alone and intercropped with soybean as follows;1 row maize to 1 row soybean (1M1S),1 row maize to 2 rows soybean (1M2S) and 1 row maize to 3 rows soybean (1M3S).The experiment was laid out in randomized complete block design with four treatments and three replications.The crops were harvested when the maize reached at heading stage (at about 35% dry matter).The results indicated significant increase in fresh biomass and dry matter production of maize fodder alone as compared to maize intercropped with soybean fodder.However,no difference (p&gt;0.05) was observed in ether extract (EE ), ash (%)and acid detergent fibre (ADF) of nutrient composition of fodder among the four treatments.After 60 days of ensiling period,silage samples were analysed for pH,dry matter (DM),crude protein (CP),ether extract (EE),neutraldetergent fibre (NDF), acid detergent fibre (ADF) and water soluble carbohydrate (WSC).All intercropped silages had higher CP values (1M1S,12.1%;1M2S,12.1%;1M3S,12.7%) than the monocrop maize (SM,8.4%) silage.The NDF and ADF levels were higher for maize silage as compared to intercropped silages. The study showed that among all intercropped silages the IM3S (1 row maize to 3 rows soybean) was preferable according to nutrient composition than other intercropped silages.

Management of Pigweed (Amaranthusspp.) in Glufosinate-Resistant Soybean in the Midwest and Mid-South

Pigweeds are among the most abundant and troublesome weed species across Midwest and mid-South soybean production systems because of their prolific growth characteristics and ability to rapidly evolve resistance to several herbicide sites of action. This has renewed interest in diversifying weed management strategies by implementing integrated weed management (IWM) programs to efficiently manage weeds, increase soybean light interception, and increase grain yield. Field studies were conducted across 16 site-years to determine the effectiveness of soybean row width, seeding rate, and herbicide strategy as components of IWM in glufosinate-resistant soybean. Sites were grouped according to optimum adaptation zones for soybean maturity groups (MGs). Across all MG regions, pigweed density and height at the POST herbicide timing, and end-of-season pigweed density, height, and fecundity were reduced in IWM programs using a PRE followed by (fb) POST herbicide strategy. Furthermore, a PRE fb POST herbicide strategy treatment increased soybean cumulative intercepted photosynthetically active radiation (CIPAR) and subsequently, soybean grain yield across all MG regions. Soybean row width and seeding rate manipulation effects were highly variable. Narrow row width (≤ 38 cm) and a high seeding rate (470,000 seeds ha−1) reduced end-of-season height and fecundity variably across MG regions compared with wide row width (≥ 76 cm) and moderate to low (322,000 to 173,000 seeds ha−1) seeding rates. However, narrow row widths and high seeding rates did not reduce pigweed density at the POST herbicide application timing or at soybean harvest. Across all MG regions, soybean CIPAR increased as soybean row width decreased and seeding rate increased; however, row width and seeding rate had variable effects on soybean yield. Furthermore, soybean CIPAR was not associated with end-of-season pigweed growth and fecundity. A PRE fb POST herbicide strategy was a necessary component for an IWM program as it simultaneously managed pigweeds, increased soybean CIPAR, and increased grain yield.

WATER USE EFFICIENCY AND WATER DISTRIBUTION RESPONSE TO DIFFERENT PLANTING PATTERNS IN MAIZE–SOYBEAN RELAY STRIP INTERCROPPING SYSTEMS

SUMMARYUnderstanding crop water use in mixed crops over sole cropping is vital for developing optimum water management systems for crop production. In this study, a two-year field experiment with typical maize (Zea mays L.) and soybean [Glycine max (L.) Merr.] relay strip intercropping (2:2 maize-to-soybean rows; 200 cm bandwidth) was carried out in the 2013 and 2014 growing seasons. The quantitative effects of various planting patterns on the water-use efficiency (WUE) and water distribution were investigated. Our results indicated that soil volumetric water content and soil evaporation in the intercropping systems showed decreasing trends in the order: maize row (MM) &lt; maize-to-soybean row (MS) &lt; soybean row (SS). The highest leaf transpiration (1.91 and 2.07 mmol m−2 s−1) for the intercropped maize was measured in each of the two years in the 20 cm maize narrow-row planting pattern and decreased thereafter. Opposite trend was observed for the intercropped soybean; the highest soybean leaf transpiration (7.01 and 6.80 mmol m−2 s−1 for 2013 and 2014, respectively) was recorded in the 70 cm. The WUE of maize and soybean intercrops was lower than that of sole crop counterparts. However, the maximum group water use efficiency (GWUE) of 26.08 and 26.20 kg ha−1 mm−1 in the 40–50 cm maize narrow-row planting pattern was, respectively, 39.6% and 23% higher compared with that of sole crops. The water equivalent ratio (WER) values ranged from 1.60–1.79, suggesting better crop water use in the intercrops over sole cropping. Planting patterns provided by 40–50 cm maize narrow-row spacing were considered the most efficient in terms of maximum total yields, GWUE and WER. These results suggest that an appropriate reduction in the spacing of narrow maize row with wide soybean row could be an efficient crop management method to achieve optimal WUE and homogeneous water distribution in maize–soybean intercropping systems.

Herbicide coverage in narrow row soybean as influenced by spray nozzle design and carrier volume

The use of reduced drift nozzles that produce larger droplet sizes that are less prone to drift will likely be required for use of future postemergence herbicide applications in soybean in the USA. Experiments to evaluate the effect of reduced drift spray nozzles on spray solution coverage were conducted in the field in Indiana. Air induction extended range (AIXR) and turbo TeeJet air induction (TTI) nozzles that produce extremely coarse to ultra coarse droplets were compared to extended range (XR) and Turbo TeeJet (TT) nozzle that produced fine to coarse droplets. Each nozzle was evaluated for spray coverage at 94 and 140 l ha−1 spray volumes using water sensitive cards. Precipitation varied between site years and resulted in differences in soybean canopy development and spray solution coverage. Coverage was greater at the top of the canopy than at the bottom of the soybean canopy as expected. An interaction occurred at the top and middle of the canopy in which the AIXR and TTI nozzles had similar coverage between the two spray volumes, whereas the XR and TT nozzles had greater coverage at 140 l ha−1 carrier volume than 94 l ha−1 carrier spray volume. Spray solution coverage at the bottom of the canopy, where target weeds would be, was similar between all nozzle types. Coverage was greater at the bottom of the canopy at 140 l ha−1 spray volume than with the 94 l ha−1 carrier volume. Spray volume has a greater influence on coverage than spray nozzle type and AIXR and TTI nozzles are less prone to coverage differences due to spray volume than the XR and TT nozzles.