Characterization of runoff and infiltration from no-till soybeans with selected winter cover crops

The influence of "living mulch" winter cover crops on soil loss, runoff amount and quality and soybean growth was studied at the Midwest Claypan Experimental runoff plots located on Mexico silt loam (Udollic Ochraqualf). Experimental treatments consisted of no-till soybeans with: 1) canada bluegrass (Poa compressa L.), 2) chickweed (Stellaria media h), 3) downy brome (Bromus tectorum L.), and 4) no cover crop (CK). Runoff, sediment, dissolved nutrients, soil water content, and plant growth characteristics were measured. For chickweed (CW), canada bluegrass (CB) and downy brome (DB) treatments, runoff was reduced 66, 56, and 80 percent (P [less than] 0.01), and soil loss was decreased 61, 97, and 95 percent (P [less than] 0.01), respectively, vs. the CK treatment. Concentrations of dissolved NH4+-N and P04-3-P in runoff water from cover crop plots were 2 to 2.8 times higher than the CK (P [less than] 0.05). Runoff from the CK had a higher concentration of dissolved No3--N. Total amounts of dissolved N03--N losses were significantly decreased by 71, 73, and 76 percent (P [less than] 0.01) and NH4+-N losses reduced by 40, 36, and 46 percent (P [less than] 0.10) for treatments of CW, CB, and DB vs. the CK, respectively. P04-3-P losses also were decreased by 50, 21, and 39 percent for CW, CB, and DB vs. CK, but differences were not significant (P [greater than] 0.10). Lower plant populations and delayed plant development decreased soybean yield in cover crop treatments from 18 to 62 percent (P [less than] 0.01) vs. the CK.Project # G-1235-03 Agreement # 14-08-0001-G-1235-0

Role of runoff and interflow in chemical transport for claypan soils

Students supported: 2 Student AssistantsNo-tillage systems have been found to increase water runoff for some soils. This is a major concern because this increased runoff has the potential for increasing the runoff of dissolved herbicides in the spring since these chemicals are not incorporated into the soil with no-tillage systems. This study was conducted to evaluate the effects of seven longterm crop and tillage systems on runoff and saturated hydraulic conductivity. The study was conducted near Kingdom City, Missouri on a Mexico silt loam (fine, montmorillonitic, mesic Udollic Ochraqualf). Runoff records from 1983 through 1993 were collected. The seven treatments consisted of no-tillage (NT), moldboard plow (MP), and chisel plow (CP) continuous corn (Zea mays L.) and continuous soybean (Glycine max L.) and fallow (F). Saturated hydraulic conductivity (Ksat), bulk density, organic matter, and water content were determined on soil cores removed from two interrow positions (trafficked and non-trafficked) and two soil depths (0 - 125 mm, 125 - 150 mm). Tillage had a small but significant effect on runoff, Ksat, bulk density, water content at sampling, and organic matter. The Fallow treatment produced the lowest values of Ksat (0.2 mm/h), bulk density (1.3 g cm^-3), and organic matter content (0.9 percent) for the surface 125 mm, as compared to the NT, MB and CP treatments. No differences in Ksat were found (p=0.587) among NT, MP and CP tillage treatments. Complex interaction effects of tillage vs. wheel traffic (p=0.039) and tillage vs. depth (p=0.003) suggested that tillage effects on Ksat vary with interrow position and soil depth. The NT (0.301 mm mm^-3) had significantly higher field volumetric water content than MP (0.285 mm mm^-3) and CP (0.282 mm mm^-3), when averaged across crops. Plots planted to corn had greater water content (0.297 mm mm^-3) compared to soybean plots (0.281 mm mm^-3). Runoff under F was the highest in each year from 1983 to 1993. The greatest amount of runoff occurred during Period 4 (harvest to planting). Runoff was lowest during Period 1 and 2. No-tillage had significantly higher runoff than MP and CP treatments during Period 4, spring (p=0.006); Period 4, fall (p=0.011 ); Fallow period (p=0.005); and Period 1 and 2 (p=0.021). Cumulative runoff with NT was significantly (p=0.001) higher compared to MP and CP, except from 1991 to 1993 in which differences were not significant (p=0.374). Corn produced lower runoff rates than soybean at the 0.05 level in Period 4, fall. Increased runoff in NT was attributed to higher water content and subsequently lower infiltration for this soil which had a nearly impermeable subsurface argillic horizon.Project # G-2029-02 Agreement # 14-08-0001-G-2029-0

Chlordane movement during rainfall

Indoor rainfall simulation experiments were conducted to quantify the mass of technical chlordane leaving an experimental soil box in runoff, splash and leachate. The initial mass of technical chlordane was uniformly distributed throughout the soil at concentrations equal to those recommended for termite control around basement and foundation walls. Two silt loam soils and one sandy soil were studied. The mass of chlordane in runoff adsorbed to organic matter was estimated to be 16 times the mass of chlordane in runoff adsorbed to clay. For a soil with a clay-to-organic-matter ratio as high as 66, the mass of chlordane in runoff appears to be predominantly a function of clay content. For a soil with a clay-to-organic-matter ratio as low as 2 to 5, the mass of chlordane in runoff appears to be predominantly a function of organic matter content. An increase in rainfall intensity from 51 to 102 mm/hr increased chlordane mass in runoff by 300 to 500 percent. This increase in rainfall intensity increased the chlordane-to-sediment mass ratio in the runoff by 7 to 18 percent. The chlordane mass in runoff was 5 to 9 times as great as the mass of bromide in runoff. The chlordane mass in splash was 25 percent of the chlordane mass in runoff. Only the sandy soil at the higher rainfall intensity produced leachate. The chlordane mass in this leachate during the rainfall period was 37 percent of the chlordane mass in runoff and 264 percent of the chlordane mass in splash. The total chlordane mass which left the soil box by runoff, splash and leachate was equivalent to 4 to 44 mg per square foot of treated surface. This amounted to 0.03 to 0.31 percent of the original chlordane mass applied to the experimental soil box. This could potentially occur from previous legal surface applications in agriculture and turf management, from more recent illegal surface applications in agriculture and turf management, from proper use (according to label directions) as a subsurface termiticide but where depth of untreated cover soil was insufficient, from improper use as a subsurface termiticide where treated soil remained uncovered at the surface or from disturbance by new construction of large areas treated in previous years. This type of horizontal movement of chlordane and other organochlorine pesticides has been documented. Bennett et al. (1974) measured 70 ppb of gamma chlordane in the top five inches of soil located 10 feet away from a foundation wall treated 21 years earlier. Lichtenstein (1958) found higher concentrations of the organochlorine insecticides aldrin, lindane and DDT on the downslope side than on the upslope side of treated test plots. Similarly, Peach et al. (1973) found surface movement of aldrin, lindane and heptachlor toward points of lower elevation in a sloping field. Haan (1971) conducted laboratory rainfall-runoff experiments following surface treatment with aldrin, dieldrin and DDT and found that sediment carried more than twice as much pesticide mass as the water. Wauchope (1978) reviewed the literature on pesticide losses in runoff water from agricultural fields. He found that organochlorine pesticides lose about 1 percent of the total mass applied to the field through runoff. This compared to other commercial pesticides which lose 0.5 percent or less unless severe rainfall conditions occur within 2 weeks after application. Another important consideration is the mass of pesticide located within a few millimeters of the soil surface. Investigators have found that it is this zone from which pesticides are released during rainfall. Sharpley (1985) studied 5 soils and found the depth of this zone to range from 2 to 4 mm for 4 percent slopes under 50 mm/hr rainfall intensity to 13 to 37 mm for 20 percent slopes under 160 mm/hr rainfall intensity.Project # G-1432-04 Agreement # 14-08-0001-G-1423-0

Macropore effects on pesticides transport to groundwater

The objective of this investigation was to evaluate the leaching and degradation characteristics of atrazine and bromide in a field of alluvial soils under irrigated, no-till management. The experimental site was 0.1 ha in size. The soils were Sarpy (mixed, mesic Typic Udipsamments) with the surface texture varying from silt loam to loamy sand. Atrazine was applied at 2.2 kg/ha after sorghum (Sorghum bicolor) was planted. Bromide was applied at 115 kg/ha five days later. Soil cores were extracted to a depth of 150 cm which were segmented into 7.5 cm increments and were analyzed for each of the chemicals separately. The dates for sampling were one week, one month, two months, three months, and four months after application of the chemicals. As a result 1134 and 3542 soil samples were extracted for atrazine and bromide analysis, respectively. Atrazine was detected within the 15 to 22.5 cm depth increment one week after application. These data suggest that some of the atrazine can move to depth of 20 cm after one week which is probably due to the presence of macropores (1-5 mm diameter holes) open to the soil surface which were present in this field under no-till management. Atrazine was detected at very low concentrations at two and four months after application. Although extreme variability in atrazine concentrations occurred, the variations were not explained totally by differences in soil texture. The data in this study indicate some potential, although small, for atrazine contamination of groundwater.Project # G-1432-03 Agreement # 14-08-0001-G-1423-0

Field evaluation and model calibration for agricultural pesticide transport to groundwater - phase II

Students supported: 1 MS StudentCertain soil physical and chemical property data are needed to predict transport of agricultural chemicals (pesticides, herbicides, etc.) to groundwater. The objective of this investigation was to evaluate the soil variability of selected soil physical and chemical properties in a field used to study atrazine and bromide leaching. The site was divided into three areas due to differences in surface texture. Area I had a surface texture of sand, Area II sandy loam, and Area III loam. Soil physical properties were measured on 455 undisturbed soil samples taken systematically at 91 locations at five selected depths (15 to 20 cm depth increments to a depth of 85 cm) throughout the field. Additional samples were taken for measurement of organic matter content and pH. Organic matter content values of the three soil areas were similar throughout the soil profile. However, there was an additional peak (besides that at the soil surface) of organic matter content at the 100 cm depth in all areas. This was probably due to buried plant materials. Salt pH of Area I was higher down to the 65 cm depth compared to Areas II and III. Soil bulk density values throughout the soil profile were similar for the three soil areas. Interestingly, bulk density decreased with increasing soil depth which was attributed to the coarser texture of soil particles with increasing depth. Below the third depth, over 80 percent of the samples had 90 percent or more sand of which at least 85 percent was very coarse (1.0 to 2.0 mm). Saturated hydraulic conductivity values 7 of the three areas were similar for the shallow depths. At the 55 cm depth however, Area I had higher saturated hydraulic conductivity values than Areas II and III. The soil water characteristics of the three areas were similar for the five measured depths.Project # G-1572-02 Agreement # 14-08-0001-G-1572-0

Using native warm-season grass, forb and legume mixtures for biomass, livestock forage and wildlife benefits : a case study (2017)

Case StudyThis guide is a companion to MU Extension publications G9422, Integrating Practices That Benefit Wildlife With Crops Grown for Biomass in Missouri, and G9423, Mixtures of Native Warm-Season Grasses, Forbs and Legumes for Biomass, Forage and Wildlife Habitat, which outlines the benefits of using these mixtures of native warm-season forages and provides information to help landowners make informed decisions on enhancing wildlife habitats while producing crops for biomass. Establishment and management practices, as well as yield results, are presented as a case study in this guide so that others can implement similar practices on their property

Soil water infiltration affected by topsoil thickness in row crop and switchgrass production systems

Conversion of annual grain crop systems to biofuel production systems can restore soil hydrologic function; however, information on these effects is limited. Hence, the objective of this study was to evaluate the influence of topsoil thickness on water infiltration in claypan soils for grain and switchgrass (Panicum virgatum L.) production systems. The experiment was performed at the University of Missouri South Farm (38°54′N, 92°16′W) on a Mexico silt loam (Vertic Luvisols) soil. Since 2009, plots were planted with either switchgrass or a corn (Zea mays L.)-soybean (Glycine max (L.) Merr.) rotation. Infiltration rates were measured using ponded infiltrometers during two years (2014 and 2015) under switchgrass and grain crop management each with two levels of topsoil thickness (0 and 37.5 cm). Physically-based Parlange and Green-Ampt infiltration models were used to estimate saturated hydraulic conductivity (Ks) and sorptivity (S) parameters. Switchgrass planted on degraded soil (shallow topsoil treatment) resulted in greater Ks, S, qs (quasi-steady infiltration rate) and Kfs (field-saturated hydraulic conductivity) values than with row crop management for both 2014 and 2015 measurement years. Results for selected 24-hour mean frequency (11.8, 14.2, and 16.2 cm) storms showed that switchgrass production systems enhanced estimated water infiltration, reduced estimated runoff, and decreased estimated time from water ponding to end of ponding compared with row crop management. Switchgrass is recommended to be planted on degraded soils especially in claypan landscapes for improved water use

The influence of external factors on bacteriophages—review

The ability of bacteriophages to survive under unfavorable conditions is highly diversified. We summarize the influence of different external physical and chemical factors, such as temperature, acidity, and ions, on phage persistence. The relationships between a phage’s morphology and its survival abilities suggested by some authors are also discussed. A better understanding of the complex problem of phage sensitivity to external factors may be useful not only for those interested in pharmaceutical and agricultural applications of bacteriophages, but also for others working with phages

Study of cropping effects on soil properties related to water infiltration, runoff and soil loss using simple laboratory methods

The influence of 'living mulch' winter cover crops on soil loss, runoff amount and quality and soybean growth was studied at the Midwest Claypan Experimental runoff plots located on Mexico silt loam (Udollic Ochraqualf). Experimental treatments consisted of no-till soybeans with: 1) canada bluegrass (Poa compressa L.), 2) chickweed (Stellaria media h), 3) downy brome (Bromus tectorum L.), and 4) no cover crop (CK). Runoff, sediment, dissolved nutrients, soil water content, and plant growth characteristics were measured. For chickweed (CW), canada bluegrass (CB) and downy brome (DB) treatments, runoff was reduced 66, 56, and 80 percent (P [less than] 0.01), and soil loss was decreased 61, 97, and 95 percent (P [less than] 0.01), respectively, vs. the CK treatment. concentrations of dissolved NH4+-N and P04-3-P in runoff water from cover crop plots were 2 to 2.8 times higher than the CK (P [less than] 0.05). Runoff from the CK had a higher concentration of dissolved No3--N. Total amounts of dissolved N03--N losses were significantly decreased by 71, 73, and 76 percent (P [less than] 0.01) and NH4+-N losses reduced by 40, 36, and 46 percent (P [less than] 0.10) for treatments of cw, CB, and DB vs. the CK, respectively. P04-3-P losses also were decreased by 50, 21, and 39 percent for CW, CB, and DB vs. CK, but differences were not significant (P [greater than] 0.10). Lower plant populations and delayed plant development decreased soybean yield in cover crop treatments from 18 to 62 percent (P [less than] 0.01) vs. the CK.Project # G-916-02 Agreement # 14-08-0001-G-916-0