- Authors:
- Anand, K. V.
- Katyal, V.
- Gangwar, B.
- Source: Indian Journal of Agricultural Science
- Volume: 73
- Issue: 9
- Year: 2003
- Summary: An experiment was conducted in Akola, Parbhani and Rahuri, Maharashtra, India to evaluate the productivity of various cropping sequences. In Akola (1987-88 to 1997-98) representing Vidharbha zone, the cropping sequence involving upland cotton ( Gossypium hirsutum)-groundnut ( Arachis hypogaea) was the most suitable and efficient, resulting in the highest grain-equivalent yield (10 079 kg ha -1 year -1), productivity (43.82 kg day -1 ha -1 wheat grain equivalent), profitability (49 539 rupees ha -1 year -1), economic efficiency (135.7 rupees day -1 ha -1) and land use efficiency (90.0%), and good benefit:cost ratio (16.57) and stability (0.68). However, in terms of energetics, soyabean ( Glycine max)-groundnut sequence was superior. In Central Maharashtra Plateaux Zone, cotton-groundnut sequence was also identified as the most efficient based on an 8-year study at Parbhani (1990-91 to 1997-98). This sequence gave the highest yield (12 060 kg ha -1 year -1 wheat grain equivalent), productivity (50.04 kg day -1 ha -1), profitability (62 053 rupees ha -1 year -1), economic efficiency (170.0 rupees day -1 ha -1) and land use efficiency (85%), with moderate system stability (0.59). In terms of energetics, soyabean-Indian mustard ( Brassica juncea) was superior. At Rahuri, representing western Maharashtra scarcity zone, sole sugarcane recorded the highest net return (93 429 rupees ha -1 year -1), economic efficiency (255.9 rupees ha -1 day -1) and benefit:cost ratio (19.96). Sorghum ( Sorghum bicolor)-cabbage ( Brassica oleracea var. capitata)-cowpea ( Vigna unguiculata) was equally profitable for fodder, resulting in a wheat grain yield equivalent of 22 793 kg ha -1 year -1, productivity of 94.2 kg day -1 ha -1, profitability of 81 733 rupees ha -1 year -1, economic efficiency of 223.9 rupees day -1 ha -1, and carbohydrate production of 4.69 g 10 6/ha.
- Authors:
- Source: Soil Science Society of America Journal
- Volume: 66
- Issue: 6
- Year: 2002
- Summary: Changes agricultural management can potentially increase the accumulation rate of soil organic C (SOC), thereby sequestering CO2 from the atmosphere. This study was conducted to quantify potential soil C sequestration rates for different crops in response to decreasing tillage intensity or enhancing rotation complexity, and to estimate the duration of time over which sequestration may occur. Analyses of C sequestration rates were completed using a global database of 67 long-term agricultural experiments, consisting of 276 paired treatments. Results indicate, on average, that a change from conventional tillage (CT) to no-till (NT) can sequester 57 +/- 14 g C m(-2) yr(-1), excluding wheat (Triticum aestivum L.)-fallow systems which may not result in SOC accumulation with a change from CT to NT. Enhancing rotation complexity can sequester an average 20 +/- 12 g C m(-2) yr(-1), excluding a change from continuous corn (Zea mays L.) to corn-soybean (Glycine mar L.) which may not result in a significant accumulation of SOC. Carbon sequestration rates, with a change from CT to NT, can be expected to peak in 5 to 10 yr with SOC reaching a new equilibrium in 15 to 20 yr. Following initiation of an enhancement in rotation complexity, SOC may reach a new equilibrium in approximately 40 to 60 yr. Carbon sequestration rates, estimated for a number of individual crops and crop rotations in this study, can be used in spatial modeling analyses to more accurately predict regional, national, and global C sequestration potentials.
- Authors:
- Albrecht, A.
- Sa, J. C. D.
- Ogle, S. M.
- Denef, K.
- Feller, C.
- Six, J.
- Source: Agronomie
- Volume: 22
- Issue: 7
- Year: 2002
- Summary: The long-term stabilization of soil organic matter (SOM) in tropical and temperate regions is mediated by soil biota (e. g. fungi, bacteria, roots and earthworms), soil structure (e. g. aggregation) and their interactions. On average, soil C turnover was twice as fast in tropical compared with temperate regions, but no major differences were observed in SOM quality between the two regions. Probably due to the soil mineralogy dominated by 1:1 clay minerals and oxides in tropical regions, we found a higher aggregate stability, but a lower correlation between C contents and aggregate stability in tropical soils. In addition, a smaller amount of C associated with clay and silt particles was observed in tropical versus temperate soils. In both tropical and temperate soils, a general increase in C levels (approximate to 325 +/- 113 kg C.ha(-1).yr(-1)) was observed under no-tillage compared with conventional tillage. On average, in temperate soils under no-tillage, compared with conventional tillage, CH4 uptake (approximate to0.42 +/- 0.10 kg C-CH4.ha(-1) yr(-1)) increased and N2O emissions increased (approximate to 1.95 +/- 0.45 kg N-N2O.ha(-1).yr(-1)). These increased N2O emissions lead to a negative global warming potential when expressed on a CO2 equivalent basis.
- Authors:
- Barrett, D. J.
- Galbally, I. E.
- Graetz, R. D.
- Source: Global Change Biology
- Volume: 7
- Issue: 8
- Year: 2001
- Authors:
- Lal, R.
- Kimble, J. M.
- Follett, R. F.
- Year: 2001
- Summary: Grazing lands represent the largest and most diverse land resource-taking up over half the earth's land surface. The large area grazing land occupies, its diversity of climates and soils, and the potential to improve its use and productivity all contribute to its importance for sequestering C and mitigating the greenhouse effect and other conditions brought about by climate change. The Potential of U.S. Grazing Lands to Sequester Carbon and Mitigate the Greenhouse Effect gives you an in-depth look at this possibility.
- Authors:
- Ruiz-Suárez, L. G.
- González-Avalos, E.
- Source: Bioresource Technology
- Volume: 80
- Issue: 1
- Year: 2001
- Authors:
- Source: Agroforestry Systems
- Volume: 52
- Issue: 3
- Year: 2001
- Summary: Frequent burning and grazing and cultivation of cash crops increasingly threaten forest patches in hilly grassland in Northeast Luzon, yet their importance as a resource with multiple environmental functions and forest products persists. The aim of this study is to identify different types of forest patches, and their condition under present land-use intensification, and discuss prospects for their integration into sustainable local farming systems. Five types of forest patches are distinguished, both natural and planted ones, including rows of trees, woody patches, gallery forests, hill-slope forests and homegarden conglomerations. Natural woody patches and gallery forests in Imperata grassland are subject to degradation and land-use conversion under conditions of agricultural intensification. Woody patches in grassland affected by frequent burning and grazing cover small areas (66% below 50 m(2) as opposed to 28% in protected grassland) and contain relatively few woody plant species (25 woody species in total as opposed to 82 where protected). Yet where well managed, they may provide a variety of products for sale and subsistence, covering emergency needs and giving off-season cash income to rural communities. Moreover they serve like the gallery forest various ecological functions, carrying valuable indigenous tree species, retaining soil base nutrients, providing a continuous supply of organic matter and intercepting fine earth soil particles removed from bare surfaces. It is suggested that forest- patch management systems may be developed, taking into account both patch diversity and the diverse needs of rural communities, and to strengthen existing and undervalued functions of forest patches as permanent elements in an agricultural landscape.
- Authors:
- Source: Nutrient Cycling in Agroecosystems
- Volume: 61
- Issue: 1-2
- Year: 2001
- Summary: In recent years and in some situations the status of soil organic matter (SOM) has deteriorated considerably due to long periods of continuous cultivation and limited external inputs in the form of mineral fertilizers. Deterioration of SOM varies by agro-ecological zones, by soil types and by cropping patterns. It is more intense in East Africa, followed by coastal West Africa and Southern Africa and least intensive in the Sahel and Central Africa. It is also more serious in areas under low-input agriculture irrespective of the prevailing cropping system. The major consequence of the decrease in SOM in the tropics is lower agricultural productivity with a direct negative effect on food security. While biophysical dynamics of SOM have been extensively covered in the literature, social considerations have not received similar attention. This paper examines the social, economic and policy factors associated with the management of tropical soil organic matter. Empirical data from a range of environments in Africa show that SOM improvement options yield a positive return to land as well as labour. However, there are a number of constraints. Social constraints are related to the large quantities of organic matter that are required (case of farmyard manure), the competitive uses for the material (case of crop residues), land and labour requirements, and gender-related issues. From a policy stand point, unsecured tenure rights together with price distortions and other market failures may be important constraints. Challenges for sustainable management of SOM are identified. These include management conflicts, land tenure arrangements, the divergence in goals between individuals and society, land and labour requirements, inadequate support systems for land users, profitability issues, the role of subsidies, and the absence of national action plans. A number of opportunities are identified that could enhance the improvement or maintenance of SOM. These include: exploring the need and potential role of community-based SOM management practices; development of an integrated plant nutrient management strategy involving both organic and inorganic inputs; and development of concrete national action plans. It is argued that because externalities of SOM improvement or maintenance extend beyond the farmer's fields, SOM investment may require cost sharing between individuals and the society. Policies on subsidies need to be reconsidered. Research priorities are identified that require closer collaboration between scientists from a variety of disciplines.
- Authors:
- Fernandes, S. V.
- Martin-Neto, L.
- Amado, T. J. C.
- Mielniczuk, J.
- Bayer, C.
- Source: Soil & Tillage Research
- Volume: 54
- Issue: 1-2
- Year: 2000
- Summary: Soil organic matter decline and associated degradation of soil and environmental conditions under conventional tillage in tropical and subtropical regions underline the need to develop sustainable soil management systems. This study aimed first to evaluate the long-term effect (9 years) of two soil-tillage systems (conventional tillage: CT, and no-tillage: NT) and two cropping systems (oat (Avena strigosa Schreb)/maize (Zea mays L.): O/M; and oat+common vetch (Vicia sativa L.)/ maize+cowpea (Vigna unguiculata (L.) Walp): O+V/M+C without N fertilization on total organic carbon (TOC) and total nitrogen (TN) concentrations in a sandy clay loam Acrisol in southern Brazil. The second objective was to assess soil potential for acting as an atmospheric CO2 sink. Under NT an increase of soil TOC and TN concentrations occurred, in both cropping systems, when compared with CT. However, this increase was restricted to soil surface layers and it was higher for O+V/M+C than for O/M, The O+V/M+C under NT, which probably results in the lowest soil organic matter losses (due to erosion and oxidation) and highest addition of crop residues, had 12 Mg ha(-1) more TOC and 0.9 Mg ha(-1) more TN in the 0-30.0 cm depth soil layer, compared with O/M under CT which exhibits highest soil organic matter losses and lowest crop residue additions to the soil. These increments represent TOC and TN accumulation rates of 1.33 and 0.10 Mg ha(-1) per year, respectively. Compared with CT and O/M, this TOC increase under NT and O+V/M+C means a net carbon dioxide removal of about 44 Mg ha(-1) from the atmosphere in 9 years. NT can therefore be considered, as it is in temperate climates, an important management strategy for increasing soil organic matter. In the tropicals and subtropicals, where climatic conditions cause intense biological activity, in order to maintain or increase soil organic matter, improve soil quality and contribute to mitigation of CO2 emissions, NT should be associated with cropping systems resulting in high annual crop residue additions to soil surface. (C) 2000 Elsevier Science B.V. All rights reserved.
