**2.2 Growing season practices**

Soybean producers make decisions throughout the year that impact final yield, value, and profit from their annual crop. Many of the most critical decisions occur at the beginning of and throughout the growing season. From the moment a soybean seed is planted to harvest, producers choose (or decide against) a multitude of practices including crop rotation, row spacing, population density, irrigation, post-emergence fertilization, and pest management. Maximizing a potential soybean crop is directly connected to previous field usage. Crop rotation or the process of growing different crops in sequenced seasons within the same field is a common practice in soybean production. Corn (*Zea mays*) and soybean rotations are advantageous because of corn's high nitrogen demand which can be alleviated through *Bradyrhizobium japonicum* nitrogen fixation in soybean nodules. Corn and soybean rotations also exhibit beneficial energy balance and grain yield improvement [13, 40]. Rotations including corn and soybeans as well as wheat (*Triticum*), oats (*Avena sativa*), barley (*Hordeum vulgare*), cotton (*Gossypium*), and forageable pasture have also shown potential for economic and environmental gains [22, 41, 42]. Although depending on crop sequences, new management practices may be needed. For example, alfalfa or clover following soybeans would require liming for maximum production as those crops prefer a slightly higher pH [43].

Protecting and revitalizing the soil through non-harvested crops planted between soybean growing seasons or cover cropping is also beneficial. Cover crops protect the soil that would otherwise be farrow and replenish nutrients assimilated into the soybean plant [9, 22, 43]. Furthermore, cover crops can beneficially reduce weed pressure, lessen soil compaction, and improve water conservation [44–46]. However, cover crops increase annual cost and have not been shown to increase soybean yield which can negatively impact certain producer's net profit [47]. Many farmers who receive enough growing degree units throughout the year also limit farrow fields by double cropping with soybean. Soybean and wheat double crop systems have exhibited high economic returns for producers in both field and modeling research [48, 49]. Double cropped soybeans exhibit lower yield due to late planting and decreased leafarea-index potential, but this can be mitigated with early maturing varieties [50, 51]. Intercropping or growing at least two crops simultaneously is another, less-common option for soybean production. Corn and soybean intercropping can increase yields for both crops with the proper seeding rates [52, 53]. Wheat and soybean intercropping also displays positive yield response [54, 55]. Sugarcane (*Saccharum officinarum*) and soybean interspecific relationships increase sugarcane yield and improves rhizospheric activity while reducing soybean yield [56]. While intercropping can enhance value for soybean producers, it is unsuitable for most large-scale production systems.

After choosing a cropping system, soybean producers must then determine the proper row spacing and population density for their environment. The appropriate balance between row space and plant density is critical for maximum soybean production and reliable economic returns. Narrow rows and high plant densities both correlate with quickened canopy closure and weed suppression [57–60]. Increased plants per field also increase cost; however, subsequent increased yield and profit overcomes the cost [61–63]. As soybeans emerge and grow, the next consideration for producers is irrigation. This localized decision can be based upon historical precipitation records, predicted forecasts, day-to-day weather events, or a combination of factors. In the absence of natural precipitation, irrigation is vital to soybean production as water deficiencies inhibit yield potential [64–67]. Irrigation can also be optimized spatially throughout a field with variable rate techniques and temporally across the growing season by targeting specific growth stages [68, 69]. Fertigation applications can be used to combine applications of post-emergent fertilizer with irrigation. Other methods of post-emergent fertilization including foliar spray and direct-to-soil applications are more common solutions for growing season nutrient issues. Plant tissue sampling and analysis can be coupled with soil samples to determine in-season soil deficiencies and to prescribe further applications [9, 21, 26]. As soybean increases nitrogen uptake during reproductive stages when bacterial fixation may be diminishing, soil or foliar nitrogen applications are typical yet usually ineffective. While limited yield increases can be seen from supplemental nitrogen applications or various nutrient combinations, the economic returns generally fail to cover the cost of application [70–73]. Foliar nutrient applications have shown minor impacts on seed protein and oil content; however, these results are inconsistent amongst experiments [74, 75]. A location-specific, comprehensive nutrient management plan that accounts for all other agronomic practices is the best method for maximizing yield and economic returns in soybean production.

#### **3. Pest management**

#### **3.1 Insect pests**

Insect and insect-like pests of soybean vary greatly ranging from aphids to stinkbugs to loopers to beetles. Which insects are the major pests and potential pest

**33**

*Soybean Production, Versatility, and Improvement DOI: http://dx.doi.org/10.5772/intechopen.91778*

bug (*Megacopta cribraria* Fabricius) [76–81].

cultivars [76–81].

soybean crops are grown.

**3.2 Weeds**

impact on soybean varies significantly from year to year and depends on the region the soybean crop is grown. Total damage by insects is a little ambiguous but yield losses of up to 80% have been reported [76]. Some prominent insect pests include soybean aphids (*Aphis glycines*), Japanese beetle (*Popillia japonica* Newman), Mexican bean beetle (*Epilachna varivestis* Mulsant), two-spotted spider mites (*Tetranychus urticae*), brown marmorated and red banded stinkbug (*Halyomorpha halys* and *Piezodorous guildinii*), bean leaf beetle (*Cerotoma trifurcata*), and kudzu

Insecticides constitute a large portion of insect management as they are used to control most insect pests and in some cases are the primary method of control [80]. Integrated pest management (IPM) is becoming more common among growers due to its ability to reduce pesticide use, non-pests affected, workers' exposure to pesticides, and the likelihood insecticide resistance [82, 83]. Additionally, it has been found to be effective at reducing damage done by pests equivalent to conventional methods [84]. IPM works similarly for all pests. It involves monitoring fields to determine which pests are present, determining which pesticides can and should be used, and incorporating cultural management practices [83]. For insects, trap cropping and sweep nets are used to monitor and determine which insect pests are present [85, 86]. The cultural practices used in insect management include altering planting date and row spacing, using no-till fields, and using resistant soybean

Weeds are considered one of the most damaging, if not the most damaging pests, in soybean [87]. About 37% of global production of soybean is affected by soybean, while 23% of global production is affected by other pests [88]. In the United States alone, it has caused losses of several million US dollars each year [87]. Weeds pose a problem for soybean crops since they compete for nutrients, space, and other resources [89]. There are many different weed pests that compete with soybean, some of which include common waterhemp (*Amaranthus rudis*), Canadian horseweed (*Conyza canadensis*), giant ragweed (*Ambrosia trifida*), ivy-leaf morning glory (*Ipomea hederacea*), common cocklebur (*Xanthium strumarium*), Johnsongrass (*Sorghum halepense*), and pigweed (*Amaranthus* spp.) [90, 91]. It is important to note that which weeds are found in a particular field depends largely on where the

Management of weeds is largely done through integrated pest management. This involves using herbicides along with herbicide resistant soybean varieties and cultural practices [87, 92]. There are many different classes of herbicides that include enzyme inhibitors, lipid synthesis inhibitors, photosystems diverters, nucleic acid inhibitors, and auxin inhibitors [93]. Historically, herbicides have been a large part of weed management and will most likely remain significant due to effectiveness and limited efficiency through other individual methods [87]. Furthermore, herbicide effectiveness can be improved by using herbicide resistant soybean, such as glyphosate resistant Roundup Ready soybean. Although since weeds can develop resistance to herbicides, it is important to incorporate other management practices [87]. One such method is herbicide spray timing. A common management practice involves pre- and postemergence herbicide applications. This involves spraying herbicides before and a few days after the soybean plants have emerged to reduce any damage to the soybean plants [94]. Additionally, cultural control practices are used including crop rotations, planting in narrow rows and proper fertilization to promote crop competition, and cultivation [92]. Crop rotations allow for different herbicides to be used which in turn helps to prevent the development of herbicide

*Soybean Production, Versatility, and Improvement DOI: http://dx.doi.org/10.5772/intechopen.91778*

impact on soybean varies significantly from year to year and depends on the region the soybean crop is grown. Total damage by insects is a little ambiguous but yield losses of up to 80% have been reported [76]. Some prominent insect pests include soybean aphids (*Aphis glycines*), Japanese beetle (*Popillia japonica* Newman), Mexican bean beetle (*Epilachna varivestis* Mulsant), two-spotted spider mites (*Tetranychus urticae*), brown marmorated and red banded stinkbug (*Halyomorpha halys* and *Piezodorous guildinii*), bean leaf beetle (*Cerotoma trifurcata*), and kudzu bug (*Megacopta cribraria* Fabricius) [76–81].

Insecticides constitute a large portion of insect management as they are used to control most insect pests and in some cases are the primary method of control [80]. Integrated pest management (IPM) is becoming more common among growers due to its ability to reduce pesticide use, non-pests affected, workers' exposure to pesticides, and the likelihood insecticide resistance [82, 83]. Additionally, it has been found to be effective at reducing damage done by pests equivalent to conventional methods [84]. IPM works similarly for all pests. It involves monitoring fields to determine which pests are present, determining which pesticides can and should be used, and incorporating cultural management practices [83]. For insects, trap cropping and sweep nets are used to monitor and determine which insect pests are present [85, 86]. The cultural practices used in insect management include altering planting date and row spacing, using no-till fields, and using resistant soybean cultivars [76–81].

#### **3.2 Weeds**

*Legume Crops - Prospects, Production and Uses*

Protecting and revitalizing the soil through non-harvested crops planted between soybean growing seasons or cover cropping is also beneficial. Cover crops protect the soil that would otherwise be farrow and replenish nutrients assimilated into the soybean plant [9, 22, 43]. Furthermore, cover crops can beneficially reduce weed pressure, lessen soil compaction, and improve water conservation [44–46]. However, cover crops increase annual cost and have not been shown to increase soybean yield which can negatively impact certain producer's net profit [47]. Many farmers who receive enough growing degree units throughout the year also limit farrow fields by double cropping with soybean. Soybean and wheat double crop systems have exhibited high economic returns for producers in both field and modeling research [48, 49]. Double cropped soybeans exhibit lower yield due to late planting and decreased leafarea-index potential, but this can be mitigated with early maturing varieties [50, 51]. Intercropping or growing at least two crops simultaneously is another, less-common option for soybean production. Corn and soybean intercropping can increase yields for both crops with the proper seeding rates [52, 53]. Wheat and soybean intercropping also displays positive yield response [54, 55]. Sugarcane (*Saccharum officinarum*) and soybean interspecific relationships increase sugarcane yield and improves rhizospheric activity while reducing soybean yield [56]. While intercropping can enhance value for soybean producers, it is unsuitable for most large-scale production systems. After choosing a cropping system, soybean producers must then determine the proper row spacing and population density for their environment. The appropriate balance between row space and plant density is critical for maximum soybean production and reliable economic returns. Narrow rows and high plant densities both correlate with quickened canopy closure and weed suppression [57–60]. Increased plants per field also increase cost; however, subsequent increased yield and profit overcomes the cost [61–63]. As soybeans emerge and grow, the next consideration for producers is irrigation. This localized decision can be based upon historical precipitation records, predicted forecasts, day-to-day weather events, or a combination of factors. In the absence of natural precipitation, irrigation is vital to soybean production as water deficiencies inhibit yield potential [64–67]. Irrigation can also be optimized spatially throughout a field with variable rate techniques and temporally across the growing season by targeting specific growth stages [68, 69]. Fertigation applications can be used to combine applications of post-emergent fertilizer with irrigation. Other methods of post-emergent fertilization including foliar spray and direct-to-soil applications are more common solutions for growing season nutrient issues. Plant tissue sampling and analysis can be coupled with soil samples to determine in-season soil deficiencies and to prescribe further applications [9, 21, 26]. As soybean increases nitrogen uptake during reproductive stages when bacterial fixation may be diminishing, soil or foliar nitrogen applications are typical yet usually ineffective. While limited yield increases can be seen from supplemental nitrogen applications or various nutrient combinations, the economic returns generally fail to cover the cost of application [70–73]. Foliar nutrient applications have shown minor impacts on seed protein and oil content; however, these results are inconsistent amongst experiments [74, 75]. A location-specific, comprehensive nutrient management plan that accounts for all other agronomic practices is the best method for maximizing yield and economic returns in soybean production.

Insect and insect-like pests of soybean vary greatly ranging from aphids to stinkbugs to loopers to beetles. Which insects are the major pests and potential pest

**32**

**3. Pest management**

**3.1 Insect pests**

Weeds are considered one of the most damaging, if not the most damaging pests, in soybean [87]. About 37% of global production of soybean is affected by soybean, while 23% of global production is affected by other pests [88]. In the United States alone, it has caused losses of several million US dollars each year [87]. Weeds pose a problem for soybean crops since they compete for nutrients, space, and other resources [89]. There are many different weed pests that compete with soybean, some of which include common waterhemp (*Amaranthus rudis*), Canadian horseweed (*Conyza canadensis*), giant ragweed (*Ambrosia trifida*), ivy-leaf morning glory (*Ipomea hederacea*), common cocklebur (*Xanthium strumarium*), Johnsongrass (*Sorghum halepense*), and pigweed (*Amaranthus* spp.) [90, 91]. It is important to note that which weeds are found in a particular field depends largely on where the soybean crops are grown.

Management of weeds is largely done through integrated pest management. This involves using herbicides along with herbicide resistant soybean varieties and cultural practices [87, 92]. There are many different classes of herbicides that include enzyme inhibitors, lipid synthesis inhibitors, photosystems diverters, nucleic acid inhibitors, and auxin inhibitors [93]. Historically, herbicides have been a large part of weed management and will most likely remain significant due to effectiveness and limited efficiency through other individual methods [87]. Furthermore, herbicide effectiveness can be improved by using herbicide resistant soybean, such as glyphosate resistant Roundup Ready soybean. Although since weeds can develop resistance to herbicides, it is important to incorporate other management practices [87]. One such method is herbicide spray timing. A common management practice involves pre- and postemergence herbicide applications. This involves spraying herbicides before and a few days after the soybean plants have emerged to reduce any damage to the soybean plants [94]. Additionally, cultural control practices are used including crop rotations, planting in narrow rows and proper fertilization to promote crop competition, and cultivation [92]. Crop rotations allow for different herbicides to be used which in turn helps to prevent the development of herbicide

resistant weeds [92]. Promoting crop competition through planting density allows soybean plants to grow enough to create a canopy to maximize shading of weeds [92]. Cultivation is an effective and economical way to control weeds to help minimize herbicide use [92]. All of the aforementioned management practices are parts of integrated weed management and will continue to play a significant role in control of weeds.

#### **3.3 Diseases**

Similar to the insect pests, there is a wide variety of diseases in soybean. Most diseases are caused by fungal and bacterial diseases and can be vectored by nematodes. Fungal diseases have been known to reduce yield up to 50%, while bacterial diseases have been known to cause yield loss of anywhere between 15 and 60% [76]. Which disease is the most devastating depends on the region and the year, but the most prevalent diseases include *Heterodera glycines*, *Phytophthora sojae*, *Colletotrichum truncatum*, *Septoria glycines*, and *Phakopsora pachyrhizi* [76]. Of these five diseases, *Heterodera glycines*, or soybean cyst nematode is the most economic damaging disease being found in all countries that grow soybean and causing up to 90% yield reduction in some areas [76]. **Table 2** provides an overview of some of the main soybean diseases.

From **Table 2**, it is evident that chemical pesticides still play a large role in treatment strategies against all major diseases in soybean. However, there has been a rising interest to incorporate other methods that prevent and treat diseases in soybean due to the harmful environmental and health effects of pesticides. Some other methods to control soybean diseases are seen in cultural control practices, such as increasing or decreasing tillage and crop rotation, drainage, and using resistant cultivars [103]. While the treatments listed in the above table are usually effective, there is continual research to find innovative ways to improve the control of plant diseases. One such example is the development of using hyperspectral bands for early detection of charcoal rot in soybean [104]. These researchers developed a method that involves analyzing spectral and spatial information of infected and healthy soybean in order to find wavebands that signify a soybean plant that is infected with charcoal rot [104]. This process identified six wavebands that were specific to plants infected with charcoal rot and can potentially allow for the detection of charcoal rot in crops in three days [104]. By being able to identify disease earlier, growers can minimize the damage done by that disease by removing infected plants and incorporating treatment strategies, such as pesticides or cultural controls.

The research above shows that there is interest in developing early detection for soybean pathogens. One of the other major areas of research for soybean diseases, is identifying resistance genes to promote resistant cultivars. Given that soybean cyst nematode is one of the most devastating soybean diseases there has been a lot of research done to identify genes involved with resistance to soybean cyst nematode. The main resistance gene in soybean to cyst nematode is the Rhg1 gene, which encodes an amino acid transporter [105, 106]. This gene confers partial resistance and has been shown to reduce reproduction of soybean cyst nematode and improve yield in fields that are infected with soybean cyst nematode [78]. Even though there are resistant cultivars available, they do not permanently stop diseases. For soybean cyst nematode, it is advised to utilize cultural practices, such as using multiple resistant cultivars and rotating with non-host crops that are resistant to cyst nematode, and other methods [107]. This is a classic example of how integrated pest management involves continuously incorporating new methods to control diseases to prevent the disease from overcoming any pesticides and resistant cultivars.

**35**

*Soybean Production, Versatility, and Improvement DOI: http://dx.doi.org/10.5772/intechopen.91778*

**4. Soybean utilization and products**

*Overview of 7 prevalent diseases in soybean [95–102].*

Soybean is a valuable crop worldwide mainly because of soybean meal's nutritional

efficacy as a food and feed ingredient. A high protein content, balanced essential amino acid profile, and the presence of other beneficial nutrients all contribute to its economic and nutritional value. Soybean meal constitutes 70% of seed value while only being roughly 35% of seed dry weight [108, 109]. Furthermore, in the United States, 97% of soybean meal is used for livestock feed [109]. This overwhelming usage rate as a livestock protein source is mainly due to the presence of essential amino acids. While some livestock require other amino acids, most livestock need nine essential amino acids: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine [110]. All nine of these amino acids are found in some quantity in soybean meal [111]. For this reason, soybean meal can maximize livestock production in cattle, swine, poultry, and aquaculture. Generally, soybean meal and other soy byproducts use are limited to a supplementary or finishing role for cattle due to feed ration complications from other seed components [110, 112, 113]. Soybean meal use is highly prevalent in monogastric livestock production such as swine and poultry and is increasing in popularity for aquaculture [114, 115]. However,

**4.1 Livestock feed**

**Table 2.**

*Soybean Production, Versatility, and Improvement DOI: http://dx.doi.org/10.5772/intechopen.91778*


**Table 2.**

*Legume Crops - Prospects, Production and Uses*

control of weeds.

the main soybean diseases.

**3.3 Diseases**

resistant weeds [92]. Promoting crop competition through planting density allows soybean plants to grow enough to create a canopy to maximize shading of weeds [92]. Cultivation is an effective and economical way to control weeds to help minimize herbicide use [92]. All of the aforementioned management practices are parts of integrated weed management and will continue to play a significant role in

Similar to the insect pests, there is a wide variety of diseases in soybean. Most diseases are caused by fungal and bacterial diseases and can be vectored by nematodes. Fungal diseases have been known to reduce yield up to 50%, while bacterial diseases have been known to cause yield loss of anywhere between 15 and 60% [76]. Which disease is the most devastating depends on the region and the year, but the most prevalent diseases include *Heterodera glycines*, *Phytophthora sojae*, *Colletotrichum truncatum*, *Septoria glycines*, and *Phakopsora pachyrhizi* [76]. Of these five diseases, *Heterodera glycines*, or soybean cyst nematode is the most economic damaging disease being found in all countries that grow soybean and causing up to 90% yield reduction in some areas [76]. **Table 2** provides an overview of some of

From **Table 2**, it is evident that chemical pesticides still play a large role in treatment strategies against all major diseases in soybean. However, there has been a rising interest to incorporate other methods that prevent and treat diseases in soybean due to the harmful environmental and health effects of pesticides. Some other methods to control soybean diseases are seen in cultural control practices, such as increasing or decreasing tillage and crop rotation, drainage, and using resistant cultivars [103]. While the treatments listed in the above table are usually effective, there is continual research to find innovative ways to improve the control of plant diseases. One such example is the development of using hyperspectral bands for early detection of charcoal rot in soybean [104]. These researchers developed a method that involves analyzing spectral and spatial information of infected and healthy soybean in order to find wavebands that signify a soybean plant that is infected with charcoal rot [104]. This process identified six wavebands that were specific to plants infected with charcoal rot and can potentially allow for the detection of charcoal rot in crops in three days [104]. By being able to identify disease earlier, growers can minimize the damage done by that disease by removing infected plants and incorporating treatment strategies, such as pesticides or cultural

The research above shows that there is interest in developing early detection for soybean pathogens. One of the other major areas of research for soybean diseases, is identifying resistance genes to promote resistant cultivars. Given that soybean cyst nematode is one of the most devastating soybean diseases there has been a lot of research done to identify genes involved with resistance to soybean cyst nematode. The main resistance gene in soybean to cyst nematode is the Rhg1 gene, which encodes an amino acid transporter [105, 106]. This gene confers partial resistance and has been shown to reduce reproduction of soybean cyst nematode and improve yield in fields that are infected with soybean cyst nematode [78]. Even though there are resistant cultivars available, they do not permanently stop diseases. For soybean cyst nematode, it is advised to utilize cultural practices, such as using multiple resistant cultivars and rotating with non-host crops that are resistant to cyst

nematode, and other methods [107]. This is a classic example of how integrated pest management involves continuously incorporating new methods to control diseases to prevent the disease from overcoming any pesticides and resistant cultivars.

**34**

controls.

*Overview of 7 prevalent diseases in soybean [95–102].*
