• A generic protocol for an integrated land information system in humid subtropical highlands: a case study in Yunnan Province, China

      Fullen, Michael A.; Hocking, Trevor J.; Bock, Laurent; Li, Yongmei (University of Wolverhampton, 2004)
      This study develops a basis for a land information system for the 40 ha subtropical highland catchment of Wang Jia, Yunnan Province, China. Information, including meteorology, geology, geomorphology, biology, pedology and crop productivity, was integrated using a geomorphopedological approach and expressed as maps using GIS. The developed protocol is proposed as a generic system, applicable to agricultural land evaluation in subtropical highland catchments. The results demonstrate that Wang Jia Catchment is relatively representative of the region, in terms of geomorphological features and land cover. Catchment soils, developed from residual, colluvial and alluvial materials of sandstone, shale and dolomite on different landscapes, were still young and strongly influenced by their geological parent material. Soils were normally slightly acidic to neutral. Soil fertility varied from poor to very fertile. Maize yield was significantly correlated with soil pH, total N, available N, P and K and thus the Soil Fertility Index. In 2002, maize yield was significantly correlated with manure and urea applications. There was considerable potential to increase maize yield with modified and innovative cropping practices in the catchment. Adopted primarily as a soil conservation practice, contour cultivation did not increase maize yield compared to downslope cultivation. Polythene mulch tended to increase maize yield in most years. These results largely accord with the results from controlled research plots in the same catchment. Analysis of intra-plot variations showed that soil samples from planting pits had higher total soil organic matter, total N, available N, available P and available K than inter-row samples, but with higher standard deviations. Most soil fertility parameters for inter-row samples were more similar to traditional random composite samples. These results suggest if composite samples were taken only from inter-rows, the results would have been similar, but the risk of sampling error would have been reduced. The land information system established in this study is suitable for designing, evaluating and monitoring sustainable agricultural practices central to soil conservation and crop yield improvement and thus contributing to decision-making for sustainable agricultural land management in this region.
    • Agricultural soil properties and crop production on Lithuanian sandy and loamy Cambisols after the application of calcareous sapropel fertilizer

      Bakšienė, Eugenija; Fullen, Michael A.; Booth, Colin A. (Taylor & Francis, 2006)
      Lake-derived organic-rich mud (sapropel) is used as a soil fertilizer on sandy loam Haplic Luvisols in Lithuania. Various application rates (50, 100, 150 and 200 t ha-1) were applied to crop rotations (maize, barley, clover, winter rye, potatoes and oats) and their subsequent long-term influences on soil physico-chemical properties and crop production determined. Soil agrochemical properties were evaluated before (1984 – 1985) and after the end of the first (1989 – 1990), second (1995 – 1996) and third (2001 – 2002) crop rotations from seven treatments with four replications. In most cases, after each crop rotation, there were notable increases in pH, total absorbed bases, total nitrogen content, available phosphorus and potassium and soil organic matter content (humus). After three rotations, changes in soil acidity, total nitrogen and humus on all sapropel treatments were significant (p < 0.05), but effects on phosphorus and potassium were not significant. In comparison, for most treatments, manure produced greater improvements in soil properties than sapropel. However, after 18 years of application, sapropel did improve crop productivity almost to the level achieved by applications of manure and fertilizers. Therefore, results demonstrate there are long-term benefits of sapropel applications, namely improvements in soil properties and crop productivity.
    • 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.
    • Factors relating to soil fertility and species diversity in both semi-natural and created meadows in the West Midlands of England

      McCrea, Alison R.; Trueman, Ian C.; Fullen, Michael A. (Blackwell, 2004)
      The post-war decline in the area and diversity of neutral meadows in Britain, resulting from agricultural intensification, has prompted schemes to restore and create new habitats. Their success relies on understanding the relations between soil fertility and species diversity. We have investigated these relations, using multivariate analysis, in 28 semi-natural meadows and eight artificially created urban meadows. Mineralizable nitrogen was the most important soil characteristic in the semi-natural sites; the more N the soil contained the fewer were the species characteristic of traditional meadows. Both potassium and total magnesium favoured diversity, perhaps because their deficiency in many traditionally managed meadows jeopardizes the survival of broad-leaved species in competition with grasses. Available lead, at sub-lethal concentrations and measured as a Pb:Ca ratio, appeared to favour diversity in the semi-natural sites, possibly by inhibiting the uptake of P by competitive grasses and allowing the less competitive species associated with diversity to flourish. The main differences between the soils of the artificial and the semi-natural meadows were that the former contained more extractable P and less mineralizable N and organic matter. It seems that large soil phosphorus concentrations may be the main reason why relatively few species colonize or survive in grassland on many urban soils.
    • Long-term yield trend and sustainability of rainfed soybean–wheatsystem through farmyard manure application in a sandy loam soil of the Indian Himalayas

      Kundu, S.; Bhattacharyya, Ranjan; Prakash, Ved; Pathak, H.; Gupta, H.S.; Ladha, J.K. (Springer Verlag, 2006)
      A long-term (30 years) soybean–wheat experiment was conducted at Hawalbagh, Almora, India to study the effects of organic and inorganic sources of nutrients on grain yield trends of rainfed soybean (Glycine max)–wheat (Triticum aestivum) system and nutrient status (soil C, N, P and K) in a sandy loam soil (Typic Haplaquept). The unfertilized plot supported 0.56 Mg ha−1 of soybean yield and 0.71 Mg ha−1 of wheat yield (average yield of 30 years). Soybean responded to inorganic NPK application and the yield increased significantly to 0.87 Mg ha−1 with NPK. Maximum yields of soybean (2.84 Mg ha−1) and residual wheat (1.88 Mg ha−1) were obtained in the plots under NPK + farmyard manure (FYM) treatment, which were significantly higher than yields observed under other treatments. Soybean yields in the plots under the unfertilized and the inorganic fertilizer treatments decreased with time, whereas yields increased significantly in the plots under N + FYM and NPK + FYM treatments. At the end of 30 years, total soil organic C (SOC) and total N concentrations increased in all the treatments. Soils under NPK + FYM-treated plots contained higher SOC and total N by 89 and 58% in the 0–45 cm soil layer, respectively, over that of the initial status. Hence, the decline in yields might be due to decline in available P and K status of soil. Combined use of NPK and FYM increased SOC, oxidizable SOC, total N, total P, Olsen P, and ammonium acetate exchangeable K by 37.8, 42.0, 20.8, 30.2, 25.0, and 52.7%, respectively, at 0–45 cm soil layer compared to application of NPK through inorganic fertilizers. However,the soil profiles under all the treatments had a net loss of nonexchangeable K, ranging from 172 kg ha−1 under treatment NK to a maximum of 960 kg ha−1 under NPK + FYM after 30 years of cropping. Depletion of available P and K might have contributed to the soybean yield decline in treatments where manure was not applied. The study also showed that although the combined NPK and FYM application sustained long-term productivity of the soybean– wheat system, increased K input is required to maintain soil nonexchangeable K level.
    • Potassium balance as influenced by farmyard manure application under continuous soybean–wheat cropping system in a Typic Haplaquept

      Bhattacharyya, Ranjan; Prakash, Ved; Kundu, S.; Ghosh, B.N.; Srivastva, A.K.; Gupta, H.S. (Elsevier, 2006)
      The effect of 30 years of continuous cropping, fertilization and manuring on the potassium (K) balances, the soil K pools and the nonexchangeable K release in a Typic Haplaquept soil from Almora, India under a rainfed soybean–wheat cropping system were investigated. The apparent K balance was measured as the difference between the total K added and that removed by the crops. The results showed that the total removal of K by the crops exceeded the amount of total K applied to the soil in all the treatments showing a net negative K balance. This ranged from 3.7 in the plots under NK to 81.7 kg ha−1 year−1 in the N+FYM treated plots. Continuous annual application of recommended doses of NPK+10 t FYM (NPK+FYM) to soybean resulted in an accumulation (+56 kg K ha−1) of exchangeable K (1 N NH4OAc extractable K) in the 0–45 cm soil depth over the study period, despite the highest average annual uptake of K by the system (150.8 kg ha−1 year−1). However, there was a net depletion of exchangeable K (−80 kg K ha−1) in that soil depth under the NPK treated plots. The results also revealed that the content of non-exchangeable K decreased substantially from 3482 kg ha−1 to 2677 and 2896 kg ha−1 in the 0–45 cm soil layer after 30 years of cropping in the plots under NPK+FYM and NPK treatments, respectively. There was a significant decline in total soil K with the removal of non-exchangeable soil K in the surface (0–15 cm) soil layer (R2=0.526,Pb0.001, n=36). Thus, long-term application of non-revised recommended fertilizer rates may threaten sustainability of the rainfed continuous soybean–wheat system.