• Authors:
    • Shukla, S.
    • Harris, W. G.
    • Obreza,T. A.
    • Sartain, J. B.
    • Schumann, A. W.
    • Mann, K. K.
  • Source: Journal of Plant Nutrition and Soil Science
  • Volume: 174
  • Issue: 6
  • Year: 2011
  • Summary: Variability in soil properties is a complication for fertilization, irrigation, and amendment application. However, only limited progress has been made in managing soil variability for uniform productivity and increased water-use efficiency. This study was designed to ameliorate the poor-productivity areas of the variable sandy soils in Florida citrus groves by using frequent small irrigations and applying organic and inorganic soil amendments. Two greenhouse experiments were set up with sorghum and radish as bioassay crops in a randomized complete block design (RCBD). The factors studied were two soil-productivity classes (very poor and very good), two water contents (50% and 100% of field capacity), two amendments (phosphatic clay and Fe humate), and two amendment rates (10 and 25 g kg -1 for sorghum and 50 and 100 g kg -1 for radish). Amendments applied at 50 and 100 g kg -1 increased the water-holding capacity (WHC) of poor soil by 2- to 6-fold, respectively. The lower rates (10 and 25 g kg -1) of amendments were not effective in enhancing sorghum growth. The higher rates (50 and 100 g kg -1) doubled the radish growth as compared to the control. The results indicate that rates greater than 50 g kg -1 of both amendments were effective in improving water retention and increasing productivity. Irrigation treatment of 100% of field capacity (FC) increased the sorghum and radish growth by about 2-fold as compared with the 50%-water content treatment. The results suggest that the root-zone water content should be maintained near FC by frequent small irrigations to enhance water availability in excessively drained sandy soils. In addition, application of soil amendments in the root zone can enhance the water retention of these soils. Furthermore, managing variable sandy soils with WHC-based irrigation can increase water uptake and crop production in the poor areas of the grove.
  • Authors:
    • Booker, J.
    • Lascano, R.
    • Acosta-Martinez, V.
    • Calderon, F.
    • Zobeck, T.
    • Upchurch, D.
  • Source: Biology and Fertility of Soils
  • Volume: 47
  • Issue: 6
  • Year: 2011
  • Summary: In dryland agriculture in semiarid regions, crop establishment is not always possible because precipitation may not be sufficient. Modification of soil properties can improve the soil quality and functioning including soil water capture and storage capacity for crop production in dryland conditions. ARS scientists established a study near Lubbock, Texas in 2003 to compare the soil properties under different dryland cropping systems and tillage management. After only 3 years, this study detected increases in soil microbial community size and enzyme activities important for nutrient cycling under rotations with a winter cover crop such as cotton-rye-sorghum and haygrazer-rye compared to continuous cotton or sorghum-cotton at 0-10 cm soil depth. After 5 years, higher soil total C was found under Hay-Rye compared to the other systems. In addition, microbial properties were already impacted in all alternative systems (haygrazer-rye, cotton-rye-sorghum and cotton-sorghum) studied compared to continuous cotton. Several microbial properties indicative of increased soil water availability were also higher under the alternative rotations to continuous cotton. However, continuation of this study is vitally important for the long-term evaluation and confirmation of these trends, and their implications in water management, soil quality and crop productivity in dryland.
  • Authors:
    • Blanco-Canqui, H.
    • Mikha, M. M.
    • Presley, D. R.
    • Claassen, M. M.
  • Source: Soil Science Society of America Journal
  • Volume: 75
  • Issue: 4
  • Year: 2011
  • Summary: Inclusion of cover crops (CCs) may be a potential strategy to boost no-till performance by improving soil physical properties. To assess this potential, we utilized a winter wheat ( Triticum aestivum L.)-grain sorghum [ Sorghum bicolor (L.) Moench] rotation, four N rates, and a hairy vetch (HV; Vicia villosa Roth) CC after wheat during the first rotation cycles, which was replaced in subsequent cycles with sunn hemp (SH; Crotalaria juncea L.) and late-maturing soybean [LMS; Glycine max (L.) Merr.] CCs in no-till on a silt loam. At the end of 15 yr, we studied the cumulative impacts of CCs on soil physical properties and assessed relationships between soil properties and soil organic C (SOC) concentration. Across N rates, SH reduced near-surface bulk density (rho b) by 4% and increased cumulative infiltration by three times relative to no-CC plots. Without N application, SH and LMS reduced Proctor maximum rho b, a parameter of soil compactibility, by 5%, indicating that soils under CCs may be less susceptible to compaction. Cover crops also increased mean weight diameter of aggregates (MWDA) by 80% in the 0- to 7.5-cm depth. The SOC concentration was 30% greater for SH and 20% greater for LMS than for no-CC plots in the 0- to 7.5-cm depth. The CC-induced increase in SOC concentration was negatively correlated with Proctor maximum rho b and positively with MWDA and cumulative infiltration. Overall, addition of CCs to no-till systems improved soil physical properties, and the CC-induced change in SOC concentration was correlated with soil physical properties.
  • Authors:
    • Blanco-Canqui, H.
    • Schlegel, A. J.
    • Heer, W. F.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 144
  • Issue: 1
  • Year: 2011
  • Summary: No-till (NT) farming is considered as a potential strategy for sequestering C in the soil. Data on soil-profile distribution of C and related soil properties are, however, limited, particularly for semiarid regions. We assessed soil C pool and soil structural properties such as aggregate stability and strength to 1 m soil depth across three long-term (≥21 year) NT and conventional till (CT) experiments along a precipitation gradient in the central Great Plains of the USA. Tillage systems were in continuous winter wheat ( Triticum aestivum L.) on a loam at Hutchinson and winter wheat-sorghum [ Sorghum bicolor (L.) Moench]-fallow on silt loams at Hays and Tribune, Kansas. Mean annual precipitation was 889 mm for Hutchinson, 580 mm for Hays, and 440 mm for Tribune. Changes in profile distribution of soil properties were affected by differences in precipitations input among the three sites. At Hutchinson, NT had 1.8 times greater SOC pool than CT in the 0-2.5-cm depth, but CT had 1.5 times greater SOC pool in the 5-20-cm. At Hays, NT had 1.4 times greater SOC pool than CT in the 0-2.5-cm depth. Differences in summed SOC pool for the whole soil profile (0-1 m depth) between NT and CT were not significant at any site. The summed SOC pool with depth between NT and CT were only significant above the 5 cm depth at Hutchinson and 2.5 cm depth at Hays. At Hutchinson, NT stored 3.4 Mg ha -1 more SOC than CT above 5 cm depth. At Hays, NT stored 1.35 Mg ha -1 more SOC than CT above 2.5 cm depth. Moreover, NT management increased mean weight diameter of aggregates (MWDA) by 3 to 4 times for the 0-5-cm depth at Hutchinson and by 1.8 times for the 0-2.5-cm depth at Hays. It also reduced air-dry aggregate tensile strength (TS) for the 0-5-cm depth at Hutchinson and Hays and for the 0-2.5-cm depth at Tribune. The TS ( r=-0.73) and MWDA ( r=0.81) near the soil surface were more strongly correlated with SOC concentration at Hutchinson than at Hays and Tribune attributed to differences in precipitation input. Results suggested NT impacts on increasing SOC pool and improving soil structural properties decreased with a decrease in precipitation input. Changes in soil properties were larger at Hutchinson (880 mm of precipitation) than at Hays and Tribune (≤580 mm). While NT management did not increase SOC pool over CT for the whole soil profile, the greater near-surface accumulation of SOC in NT than in CT was critical to the improvement in soil structural properties. Overall, differences in precipitation input among soils appeared to be the dominant factor influencing NT impacts on soil-profile distribution of SOC and soil structural properties in this region.
  • Authors:
    • Caires, E. F.
    • Garbuio, F. J.
    • Churka, S.
    • Joris, H. A. W.
  • Source: Agronomy Journal
  • Volume: 103
  • Issue: 6
  • Year: 2011
  • Summary: Gypsum has been used in tropical and subtropical agriculture when subsoil acidity is an important yield-limiting factor. However, the conditions that promote increased crop yield as a result of gypsum addition in no-till (NT) systems still remain unclear. A field trial examined the effects of newly and previously surface-applied gypsum in a long-term NT system on the soil chemical properties and nutrition and yield of corn ( Zea mays L.), wheat ( Triticum aestivum L.), and soybean [ Glycine max (L.) Merr.] on a clayey Rhodic Hapludox in Parana State, Brazil. Gypsum was surface-applied at 0 and 6 Mg ha -1 in 2004 on plots that had received gypsum previously at 0, 3, 6, and 9 Mg ha -1 in 1998. Surface-applied gypsum newly and previously improved exchangeable Ca and SO 4-S availability throughout the soil profile, and increased the cumulative grain yield of the crops. Exchangeable K losses through leaching caused by gypsum application were low, and a larger mobility of exchangeable Mg as compared with exchangeable K in soil was found as a result of gypsum addition. An increase in Ca content in the corn, wheat, and soybean leaves, and in S content in the corn and wheat leaves occurred following the gypsum application. The use of gypsum showed economic viability to maximize crop grain production in a long-term NT soil with a sufficient level of exchangeable Ca (≥8 mmol c dm -3) and low levels of exchangeable Al (≤4 mmol c dm -3) and Al saturation (≤15%) in the subsoil layers (20-60 cm).
  • Authors:
    • Calonego, J. C.
    • Rosolem, C. A.
  • Source: Revista Brasileira de Ciência do Solo
  • Volume: 35
  • Issue: 3
  • Year: 2011
  • Summary: Soil water availability to plants is affected by soil compaction and other variables. The Least Limiting Water Range (LLWR) comprises soil physical variables affecting root growth and soil water availability, and can be managed by either mechanical or biological methods. There is evidence that effects of crop rotations could last longer than chiseling, so the objective of this study was to assess the effect of soil chiseling or growing cover crops under no-till (NT) on the LLWR. Crop rotations involving triticale (X Triticosecale) and sunflower (Helianthus annuus) in the fall-winter associated with millet (Pennisetum glaucum), sorghum (Sorghum bicolor) and sunn hemp (Crotalariajuncea) as cover crops preceding soybean (Glycine max) were repeated for three consecutive years. In the treatment with chiseling (performed. only in the first year), the area was left fallow between the fall-winter and summer crops. The experiment was carried out in Botucatu, Sao Paulo State, Brazil, from 2003 to 2006 on a Typic Rhodudalf. The LLWR was determined in soil samples taken from the layers 0-20 cm and 20-40 cm, after chemical desiccation of the cover crops in December of the first and third year of the experiment. Chiseling decreases soil bulk density in the 0-20 cm soil layer, increasing the LLWR magnitude by lowering the soil water content at which penetration resistance reaches 2.0 MPa; this effect is present up to the third year after chiseling and can reach to a depth of 0.40 in. Crop rotations involving sunflower + sunn hemp, triticale + millet and triticale + sunn hemp for three years prevented soil bulk density from exceeding the critical soil bulk density in the 0-0.20 in layer. This effect was observed to a depth of 0.40 m after three years of chiseling under crop rotations involving forage sorghum. Hence, chiseling and some crop rotations under no tillage are effective in increasing soil quality assessed by the LLWR.
  • Authors:
    • Campos-Magana, S. G.
    • Cadena-Zapata, M.
  • Source: Campos-Magana, SG
  • Volume: 42
  • Issue: 4
  • Year: 2011
  • Summary: A five year field experiment was conducted to assess the interaction between soil tillage levels, maize-sorghum-legume rotation and two levels of chemical fertilization at the rain feed tropical region of southeast Mexico. The purpose of this research work was to asses this interaction over the variation of some soil quality indices and the effect on the productivity of the soil-grain yield. The treatments for soil tillage were zero till and the intensive traditional soil tillage of the region. Crop rotations employed were five years maize (mmmmm), five years sorghum (sssss), two rotations; (smsms) and (msmsm) and two intercropping of legumes (f)-cereals, (fsfsf) and (fmsmf). Ninety two and 136 units of nitrogen were the two levels of fertilization and were applied only to the cereals. The evaluated soil index in the first and fifth year were organic matter (mo), water infiltration rate (ir), aggregate stability (as), ph, biomass microbiana (mb), nitrogen soluble nitrogen, soil density (sd), soil depth (sd), electrical conductivity (ec) and availability of nutrients. In general terms, the best grain yield for both sorghum and maize were obtained with the no till treatment although no big differences were observed between them. The five year sorghum mean yield under no till with fertilization levels 1 and 2 were 3.6 and 4.5 Mg/ha, whereas, with conventional tillage these were just 3.1 and 4.1 Mg/ha, respectively. The grain yield of maize with level 2 of nitrogen, with zero and traditional till were 5.1 and 4.6 Mg/ha; however, with nitrogen level 1 there were no apparent advantages of the first treatment (3.8 Mg/ha in both cases). The type of crop rotation and soil tillage level mainly affected the chemical soil index at 0 to 5 cm depth. However, no effect occurred with the way of handling crop residues and with the levels of chemical fertilization. The main values of electrical conductivity were attributed to an increase in the solubility of some elements. It was also observed that, under no till, there was an increase of the levels of soluble carbon.
  • Authors:
    • Schwartz, R. C.
    • MacDonald, J. C.
    • Tolk, J. A.
    • Baumhardt, R. L.
  • Source: Agronomy Journal
  • Volume: 103
  • Issue: 3
  • Year: 2011
  • Summary: Cattle (Bos taurus) grazing intensifies production of the dryland wheat (Triticum aestivum L.)-sorghum [Sorghum bicolor (L.) Moench]-fallow (WSF) rotation in the U. S. Southern High Plains. Stubble-mulch (SM) tillage controls weeds and counteracts soil compaction. No-till (NT) increases soil water at planting and dryland crop yields, but added grazing effects are unknown. Our objectives were to quantify dryland winter wheat and sorghum yield responses to grazing and tillage practices. At the USDA-ARS Conservation and Production Research Laboratory, Bushland, TX, we established all WSF rotation phases in triplicate ungrazed and grazed paddocks beginning 1999 on a Pullman clay loam (fine, mixed, superactive, thermic Torrertic Paleustoll) using SM tillage. During spring 2004, NT or SM tillage were superimposed within grazing main plots. Cattle gain, soil water aft er fallow, and crop yield were compared during 2005 to 2009 using a split-plot randomized complete block design. Cattle, stocked at 1.8 Mg ha(-1), grazed sorghum stover and growing wheat an average of 29 d for a mean gain of 147 kg ha(-1). Soil water at planting was unaffected by grazing, but increased from 14 to 28 mm with NT. Although grazing seldom reduced yield of wheat or sorghum, NT in ungrazed plots increased crop yields sufficiently (0.96-2.6 Mg ha(-1)) in 2008 and 2009 to off set any value added by grazing. We conclude that cumulative grazing effects in NT plots reduced soil water storage and depressed yield. We recommend post-wheat-harvest SM tillage to disrupt soil compaction and restore grazed soil productivity.
  • Authors:
    • Nalley, L. L.
    • Popp, M.
  • Source: Journal of Agricultural and Applied Economics
  • Volume: 43
  • Issue: 3
  • Year: 2011
  • Summary: Arkansas cropping pattern changes at the county level were estimated under various scenarios involving a likely decline in water availability, the development of a biomass market for renewable energy production, and the potential of a widely used carbon offset market. These scenarios are analyzed separately and jointly to determine which of the three scenarios is expected to have the largest impact on net (emissions - sequestration) greenhouse gas (GHG) emissions, renewable fuels feedstock supply, and producer net returns. Land use choices included conventional crops of rice, cotton, soybean, corn, grain sorghum, pasture, and hay. Specialty crops of loblolly pine and switchgrass were modeled for their respective potential to sequester carbon and provide feedstock for renewable fuels. GHG emissions were measured across an array of production methods for each crop. Soil and lumber carbon sequestration was based on yield, soil texture, and tillage. Using the concept of additionality in which net GHG emissions reductions compared with a baseline level were rewarded at a carbon price of $15 per ton along with $40 per dry ton of switchgrass, baled at field side, revealed that irrigation restrictions had the largest negative impact on producer net returns while also lowering net GHG emissions. Introducing the higher carbon price led to minor positive income ramifications and greatly reduced net GHG emissions. Biomass production returns were higher than the returns from the carbon offset market, however, at the cost of greater net GHG emissions. The combination of all factors led to a significant increase in switchgrass and pine production. In this scenario, approximately 16% of the total income losses with lower nonirrigated yields were offset with returns from biomass and carbon markets. Lowest statewide net GHG emissions were achieved given least irrigation fuel use and a greater than 15% increase in carbon sequestration with pine and switchgrass.
  • Authors:
    • Garcia, F.
    • Garcia, A.
    • Ernst, O.
    • Cano, J.
    • Bordoli, M.
    • Beux, L.
    • Bautes, C.
    • Barbazan, M.
    • Quincke, A.
  • Source: Agrociencia (Montevideo)
  • Volume: 15
  • Issue: 2
  • Year: 2011
  • Summary: The objectives of this study were to summarize the recent information generated in the country related to the potassium fertilization and find a tentative critical level of Potassium (K) in soil for various crops in Uruguay, using the most widely used K soil test. The data come from 50 K-response experiments in barley, wheat, corn, soybeans, sorghum, and sunflower, conducted by different working groups from 2004 to 2010, in soils with different texture and exchangeable K levels. The fertilizer rates ranged from 0 to 240 kg/ha of K 2O and in all cases the source of K was broadcasted KCl at planting date. Potassium fertilizer increased crop yield in 15 of 50 sites (Pr