• Carbon sequestration and relationship between carbon addition and storage under rainfed soybean–wheat rotation in a sandy loam soil of the Indian Himalayas

      Kundu, S.; Bhattacharyya, Ranjan; Prakash, Ved; Ghosh, B.N.; Gupta, H.S. (Elsevier, 2007)
      Soil organic matter (SOM) contributes to the productivity and physical properties of soils. Although crop productivity is sustained mainly through the application of organic manure in the Indian Himalayas, no information is available on the effects of long-term manure addition along with mineral fertilizers on C sequestration and the contribution of total C input towards soil organic C (SOC) storage. We analyzed results of a long-term experiment, initiated in 1973 on a sandy loam soil under rainfed conditions to determine the influence of different combinations of NPK fertilizer and fertilizer + farmyard manure (FYM) at 10 Mg ha−1 on SOC content and its changes in the 0–45 cm soil depth. Concentration of SOC increased 40 and 70% in the NPK + FYM-treated plots as compared to NPK (43.1 Mg C ha−1) and unfertilized control plots (35.5 Mg C ha−1), respectively. Average annual contribution of C input from soybean (Glycine max (L.) Merr.) was 29% and that from wheat (Triticum aestivum L. Emend. Flori and Paol) was 24% of the harvestable above-ground biomass yield. Annual gross C input and annual rate of total SOC enrichment were 4852 and 900 kg C ha−1, respectively, for the plots under NPK + FYM. It was estimated that 19% of the gross C input contributed towards the increase in SOC content. C loss from native SOM during 30 years averaged 61 kg C ha−1 yr−1. The estimated quantity of biomass C required to maintain equilibrium SOM content was 321 kg ha−1 yr−1. The total annual C input by the soybean–wheat rotation in the plots under unfertilized control was 890 kg ha−1 yr−1. Thus, increase in SOC concentration under long-term (30 years) rainfed soybean–wheat cropping was due to the fact that annual C input by the system was higher than the required amount to maintaining equilibrium SOM content.
    • Effect of tillage and crop rotations on pore size distribution and soil hydraulic conductivity in sandy clay loam soil of the Indian Himalayas

      Bhattacharyya, Ranjan; Prakash, Ved; Kundu, S.; Gupta, H.S. (Elsevier, 2006)
      Tillage management can affect crop growth by altering the pore size distribution, pore geometry and hydraulic properties of soil. In the present communication, the effect of different tillage management viz., conventional tillage (CT), minimum tillage (MT) and zero-tillage (ZT) and different crop rotations viz. [(soybean–wheat (S–W), soybean–lentil (S–L) and soybean–pea (S–P)] on pore size distribution and soil hydraulic conductivities [saturated hydraulic conductivity (Ksat) and unsaturated hydraulic conductivity {k(h)}] of a sandy clay loam soil was studied after 4 years prior to the experiment. Soil cores were collected after 4 year of the experiment at an interval of 75 mm up to 300 mm soil depth for measuring soil bulk density, soil water retention constant (b), pore size distribution, Ksat and k(h). Nine pressure levels (from 2 to 1500 kPa) were used to calculate pore size distribution and k(h). It was observed that b values at all the studied soil depths were higher under ZT than those observed under CT irrespective of the crop rotations. The values of soil bulk density observed under ZT were higher in 0–75 mm soil depth in all the crop rotations. But, among the crop rotations, soils under S–P and S–L rotations showed relatively lower bulk density values than S–W rotation. Average values of the volume fraction of total porosity with pores <7.5 μm in diameter (effective pores for retaining plant available water) were 0.557, 0.636 and 0.628 m3 m−3 under CT, MT and ZT; and 0.592, 0.610 and 0.626 m3 m−3 under S–W, S–L and S–P, respectively. In contrast, the average values of the volume fraction of total porosity with pores >150 μm in diameter (pores draining freely with gravity) were 0.124, 0.096 and 0.095 m3 m−3 under CT, MT and ZT; and 0.110, 0.104 and 0.101 m3 m−3 under S–W, S–L and S–P, respectively. Saturated hydraulic conductivity values in all the studied soil depths were significantly greater under ZT than those under CT (range from 300 to 344 mm day−1). The observed k(h) values at 0–75 mm soil depth under ZT were significantly higher than those computed under CT at all the suction levels, except at −10, −100 and −400 kPa suction. Among the crop rotations, S–P rotation recorded significantly higher k(h) values than those under S–W and S–L rotations up to −40 kPa suction. The interaction effects of tillage and crop rotations affecting the k(h) values were found significant at all the soil water suctions. Both S–L and S–P rotations resulted in better soil water retention and transmission properties under ZT.
    • Effects of Palm-mat Geotextiles on the Conservation of Loamy Sand Soils in East Shropshire, UK

      Bhattacharyya, Ranjan; Davies, Kathleen; Fullen, Michael A.; Booth, Colin A. (Catena Verlag, Reiskirchen, Germany, 2008)
      Some 30% of world arable land has become unproductive, largely due to soil erosion. Considerable efforts have been devoted to studying and controlling water erosion. However, there remains the need for efficient, environmentallyfriendly and economically-viable options. An innovative approach has used geotextiles constructed from Borassus aethiopum (Black Rhun Palm of West Africa) leaves to decrease soil erosion. The effectiveness of employing palmmats to reduce soil erosion have been investigated by measuring runoff, soil loss and soil splash on humid temperate soils. Twelve experimental soil plots (each measuring 1.0 x 1.0 m) were established at Hilton, east Shropshire, UK, to study the effects of geotextiles on splash erosion (six plots completely covered with Borassus mats and six non-protected bare soil plots). Soil splash was measured (10/06/02-09/02/04; total precipitation = 1038 mm) by collecting splashed particles in a centrally positioned trap in each plot. An additional field study (25/03/02-10/05/04; total precipitation = 1320 mm) of eight experimental runoff plots (10 x 1 m on a 15o slope) were used at the same site, with duplicate treatments: (i) bare soil; (ii) grassed, (iii) bare soil with 1 m palm-mat buffer zones at the lower end of the plots and (iv) completely covered with palm-mats. Runoff volume and sediment yield were measured after each substantial storm. Results indicate that total splash erosion in bare plots was 34.2 g m-2 and mean splash height was 20.5 cm. The use of Borassus mats on bare soil significantly (P<0.05) reduced soil splash height by ~31% and splash erosion by ~50%. Total runoff from bare plots was 3.58 L m-2 and total sediment yield was 8.58 g m-2. Thus, application of geotextiles as 1 m protective buffer strips on bare soil reduced runoff by ~36% and soil erosion by ~57%. Although total soil loss from the completely covered geotextile plots was ~16% less than the buffer zone plots, total runoff volume from the completely covered plots was ~94% more than the buffer zone plots. Thus, palm-mat (buffer strips) cover on vulnerable segments of the landscape is highly effective for soil and water conservation on temperate loamy sand soils.
    • Temporal changes in soil temperature at the Hilton Experimental Site, Shropshire, UK (1982-2006): Evidence of a warming trend?

      Subedi, Madhu; Fullen, Michael A. (Informaworld (Taylor & Francis), 2009)
      Soil temperature variations at different depths at a research site over a 25-year period (1982-2006) are discussed. Based on a database of 11,498 individual soil temperature measurements in loamy sand (Bridgnorth series) soils, soil temperature at the Hilton Experimental Site in Shropshire, UK, significantly increased between 1982 and 2006. The surface soil (0 cm) warmed twice as fast (∼0.1°C year-1) as soil at 100 cm depth (∼0.05°C year-1) and thus implies progressively steeper thermal gradients with soil depth through time. The trend of increase in soil temperatures at 0 cm was generally greater in winter. These observations contribute to the growing corpus of evidence of global warming.
    • Utilization of Palm-mat Geotextiles to Conserve Agricultural Soils.

      Bhattacharyya, Ranjan; Davies, Kathleen; Fullen, Michael A.; Booth, Colin A. (International Erosion Control Association (IECA), 2009)
      Previously, most studies on the effectiveness of geotextiles on soil erosion rates and processes were conducted in laboratory experiments for <1 h. Hence, at Hilton (52o33' N, 2o19' W), East Shropshire, UK, we investigated the effectiveness of employing palm-mat geotextiles (Borassus and Buriti mats) to reduce rainsplash erosion, runoff and soil loss under field conditions. This study is a component of the European Union-funded BORASSUS Project. The effects of Borassus mats on rainsplash erosion were studied for ~2 years (2002-2004), and re-established in January 2007 on a 0o slope. There were 12 experimental plots (six plots completely-covered with mats and six bare plots; each measuring 1.0 x 1.0 m). Runoff-plot studies were also conducted on the loamy sand soil at Hilton for 2 years (2002-2004) with duplicate treatments: (i) bare soil; (ii) grassed, (iii) bare soil with 1 m Borassus-mat buffer zones at the lower end of the plots and (iv) completely-covered with Borassus-mats. Each plot was 10 x 1 m on a 15o (26.6%) slope. To confirm the results, another set of experiments have been in progress at Hilton since January 2007, with one additional treatment (bare soil with 1 m Buriti-mat buffer zones) compared with the earlier experiment. Runoff and soil erosion were collected from each plot in a concrete gutter, leading to a 0.02 m3 (20 liters) capacity receptacle placed inside a 0.14 m3 (140 liters) capacity container. Results (06/10/02-02/09/04; total precipitation = 1038.3 mm) showed Borassus mats on bare soil reduced total rainsplash erosion by ~50% compared with bare plots (9.64 kg m-2; 1.97 lb ft-2). The use of Borassus mats on bare soil (during 01/22/07-01/21/08; total precipitation = 919.2 mm) also reduced soil splash erosion by ~90%. During 03/25/02-05/10/04 (total precipitation = 1319.8 mm) complete cover of Borassus mats on bare soil reduced total runoff by ~19% and soil erosion by ~64%. Furthermore, Borassus mats as 1 m buffer strips on bare soil reduced runoff by ~36% and soil erosion by ~57%. During 01/08/07-01/14/08 (total precipitation = 923.4 mm), plots with Borassus and Buriti mats as buffer strips on bare soil reduced sediment yield by ~93 and 98%, respectively, and runoff by ~83 and 63%, respectively. Buffer strips of Borassus mats were also as effective as complete cover of the same mats. Thus, utilization of palm-mat geotextiles as buffer strips on bare plots (area coverage ~10%) is highly effective for soil and water conservation.
    • Utilizing palm-leaf geotextile mats to conserve loamy sand soil in the United Kingdom.

      Bhattacharyya, Ranjan; Fullen, Michael A.; Davies, Kathleen; Booth, Colin A. (Amsterdam: Elsevier, 2009)
      Despite palm-leaf geotextile mats having the potential to advance soil conservation technologies, field studies using geotextiles as complete cover and buffer strips in reducing rates of soil erosion by water are limited. Hence, the utilization of these mats as a potential soil conservation technique is investigated at Hilton, east Shropshire, UK (52°33′5.7″N, 2°19′18.3″W). Geotextile mats constructed from Borassus aethiopum (Borassus palm of West Africa) and Mauritia flexuosa (Buriti palm of South America) leaves are termed Borassus mats and Buriti mats, respectively. Field experiments have been conducted at Hilton since January 2007, to study the effects of emplacing Borassus and Buriti mats on the erosion of a loamy sand soil. Two sets (12 plots each) of experiments were established to study the effects of Borassus and Buriti mats on splash height and splash erosion. In both sets, 6 randomly-selected plots were completely covered with mats, and the rest were bare. Ten runoff plots (10 × 1 m on a 15° slope) were also established, with duplicate treatments to study the effectiveness of these mats for soil and water conservation. The treatments were: (i) bare soil; (ii) permanent grassed; (iii) bare soil with 1 m Borassus mat buffer zones at the lower end of the plots; (iv) bare soil with 1 m Buriti mat buffer zones at the lower end of the plots and (v) completely covered with Borassus mats. Results (during 22/01/07–21/01/08; total precipitation = 919.0 mm; n = 22 sets of measurements) indicate that Borassus mat-cover on bare soil significantly (P < 0.05) reduced total soil splash erosion by 90% compared with bare plots (24.81 kg m−2). Plots with Borassus mats had 51% less mean splash height than bare plots (n = 21 sets of measurements). However, Buriti mat-cover on bare soils had no significant (P < 0.05) effect on soil splash height or splash erosion. Results of runoff plots (08/01/07–14/01/08; total precipitation = 923.4 mm; n = 29 sets of measurements) showed permanent grass plots had the smallest runoff coefficient and the largest sediment yield reduction effectiveness (SYRE). Total runoff from the Borassus buffer zone plots (4.1 L m−2) was 83% less than the bare plots and total sediment yield was 93% less than the bare plots (2.32 kg m−2). Although, Borassus buffer zone plots had similar effects in reducing soil loss to Borassus completely-covered plots, the later treatment yielded 50% more runoff. Borassus buffer strip plots had less SYRE than the Buriti buffer zone plots. Mass per unit area and thickness of both geotextiles decreased after 3 months of surface application. However, moisture sorption depth and cover percentage of both geotextiles increased. Hence, it is recommended to cover palm-mat geotextiles as buffer strips for soil and water conservation on erodible moderate slopes.