Pesticide and Nutrient Movement into Subsurface Tile Drains on a Silt Loam Soil in Indiana
The objectives of this study were to determine field‐scale pesticide and nutrient losses to subsurface tile drains over a 3‐yr period on a low organic matter and poorly structured silt loam soil under typical agricultural management practices. A subsurface drain spacing study was instrumented to measure drain discharge rates and to collect drainflow samples continuously on a flow‐proportional basis. Two replicates of three drain spacings (5, 10, and 20 m) were included in the study. Water samples were analyzed for all applied pesticides (atrazine, cyanazine, alachlor, carbofuran, terbufos, and chlorpyrifos)1 as well as major nutrients (N, P, K) and sediment. Small amounts of carbofuran, atrazine, cyanazine, and alachlor were detected in subsurface drainflow within 3 wk of pesticide application and after less than 2 cm net subsurface drainflow from the soil. This early arrival of pesticides at the drain is consistent with preferential flow concepts. Annual carbofuran losses in subsurface drainflow ranged from 0.8 to 14.1 g ha−1, or 0.05 to 0.94% of the amount applied to the soil.
 Tillage effects on soil organic carbon distribution and storage in a silt loam soil in Illinois
Interest in tillage impacts on sequestration of soil organic carbon (SOC) has increased greatly during recent years. The use of reduced and no-tillage (NT) practices generally increases the SOC concentration in surface few centimeters when compared to conventionally tilled soils. However, use of conservation tillage does not always result in increased SOC storage overall. The effects of sample handling and data expressions on the assessment of tillage-induced SOC sequestration were investigated using data collected from a tillage trial on a Thorp silt loam (US Taxonomy: fine-silty, mixed, mesic Argiaquic Argialboll; FAO: Orthic Greyzems). The tillage experiment was established in 1986 in Illinois, USA. The NT treatment used no soil disturbance except for planting. The disk tillage treatment included fall disking (7.5–10 cm deep) after corn (Zea mays L.) and spring field cultivation after soybean (Glycine max L.) production. The moldboard plowing treatment included fall moldboard plowing (20–25 cm deep) after corn, followed by spring disking (7.5–10 cm deep) and field cultivating; fall chisel plowing (30–35 cm) was done after soybean, followed by spring disking and field cultivation. Estimates of tillage impacts on SOC sequestration varied with the soil depth considered, time of sampling, and sample handling technique. Results indicated that tillage-induced changes in SOC occurred in the surface 30 cm. NT soil had greater C contents in the upper 30 cm when assessed on a concentration and volumetric basis.
 Water movement through Panoche clay loam soil
Water movement through Panoche clay loam is explained on the basis of the soil-water properties within the profile. Laboratory-determined soil water content-tension relations from 3-inch cores taken from the field every 6 inches to 5 feet were shown to provide reliable estimates of soil water behavior. Water management practices relative to favorable plant-available soil water and favorable salt balance within the profile are discussed.
 Spatial Characterization of Cone Index and Some Nutrients in a Sandy Loam Soil (Eutric Leptosol) Using the Multivariate Analysis
A multivariate analysis was performed on some soil nutrient and Cone Index (CI) data from the research and demonstration farm of the Dept. of Agricultural Sciences, University of Juba in South Sudan. The main objective of the study was to characterize the spatial distribution of the soil nutrients: N, P, K, Fe and Mn as well as soil penetration resistance CI. A Principal Component Analysis (PCA), Gaussian Mixture Model (GMM) and Hierarchical Cluster Analysis (HCA) were performed on the analyzed samples. The Bayesian Information Criterion (BIC) was used for model selection between the Equal size, Equal shape and Equal orientation (EEE) and Equal size, Equal shape and Variable orientation (EEV) models which defined the size, shape and orientation of the ellipsoid with full covariance matrices. Eigenvalues of the three major principal components F1, F2 and F3 accounted for 75.67% of the total variance of the data. From hierarchical clustering, P was observed to cluster with Fe, Mn with N which at second level clustered with K then with CI. The results of the PCA showed that Nitrate-N, Mn and Kwere strongly influenced by CI and so determining their spatial distribution. This could be associated mainly to earlier anthropogenic activities on the soil. The results of this study also showed spatial relationships between individual soil nutrients with both K and P mutually antagonistic with Nitrate-N, whereas between K and P where mutually synergistic. While P was strongly adsorbed to Fe, this was associated to lithogenic soil materials and therefore interpreted as derived from natural sources of the Eutric Leptosol. The goodness-of-fit test using the Kolmogorov-Smirnov (KS) showed that the values of the variables: CI, K, P and Fe were significant at p ≤0.05 and that the data followed normal distribution, whereas Mn and Nitrate-N were not. The KS test also corroborated the results of strong spatial dependency of each variable at less than 25%. The multivariate GMM adequately described the spatial distribution of all measured variables than the unimodal Gaussian.
 Distribution of Soil Micronutrients of Bakalori Irrigation Project, Zamfara State, Nigeria
The study was carried out to assess the distribution of soil micronutrients at Bakalori Irrigation Project, Zamfara State. Three local government areas; Maradun (Upper slope), Talata Mafara (Middle slope) and Bakura (Lower slope) were purposively sampled along Sokoto River. Three soil profile pits were dug, one in each local government of the study site, soil samples were collected from each horizon. Results showed that the soils were slightly acid to neutral with mean pH of 6.29, 6.60 and 6.62 for upper, middle and lower slope respectively. Organic carbon was low with mean values of 5.67 gkg-1, 2.79 gkg-1 and 4.72 gkg-1. CEC values were medium with the mean value of 10.76, 10.92 and 10.60 cmolkg-1. The results of available micronutrients showed that Fe was low with the mean values of 1.55 mgkg-1, 1.8 mgkg-1, and 1.83 mgkg-1, Mn was low to medium with the mean values of 0.70 mgkg-1, 0.85 mgkg-1 and 1.08 mgkg-1, Zn was medium with the mean values of 1.05 mgkg-1, 0.85-1 and 1.0 mgkg-1 and Cu was high with the mean values of 2.30 mgkg-1, 1.5 mgkg-1 and 2.58 mgkg-1 in all the three sites (upper, middle and lower slope). According to the USDA soil Taxonomy Classification System, soils of profile 1 (upper slope) were classified as Typic Endoaqualfs, soils profile 2 (middle slope) were classified as Aquic Haplustalfs and soils profile 3 (lower slope) were classified as Aquic Hapludalfs and the soils were locally named as Dosara, Matusgi and Birnin Tudu series for Maradun, Talata Mafara and Bakura soils respectively.
 Kladivko, E.J., Van Scoyoc, G.E., Monke, E.J., Oates, K.M. and Pask, W., 1991. Pesticide and nutrient movement into subsurface tile drains on a silt loam soil in Indiana (Vol. 20, No. 1, pp. 264-270). American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.
 Yang, X.M. and Wander, M.M., 1999. Tillage effects on soil organic carbon distribution and storage in a silt loam soil in Illinois. Soil and Tillage Research, 52(1-2), pp.1-9.
 Nielsen, D., Davidson, J., Biggar, J. and Miller, R., 1964. Water movement through Panoche clay loam soil. Hilgardia, 35(17), pp.491-506.
 Lomeling, D., Otwari, S.M. and Khater, Y.M., 2015. Spatial Characterization of Cone Index and Some Nutrients in a Sandy Loam Soil (Eutric Leptosol) Using the Multivariate Analysis. Journal of Experimental Agriculture International, pp.118-134.
 Dogo, A.A., Dikko, A.U., Ojanuga, A.G., Noma, S.S. and Sharu, M.B., 2017. Distribution of Soil Micronutrients of Bakalori Irrigation Project, Zamfara State, Nigeria. Asian Research Journal of Agriculture, pp.1-10.