Agricultural
intensification continues to be a major threat to sustainable development in
mountain regions of the world since it is largely associated with lower soil
fertility, increased soil erosion, pollution and eutrophication of water
bodies, reduced biodiversity, and livelihood challenges. Agroforestry, the
purposeful cultivation of trees and crops in interacting combinations, has the potential
to provide environmental benefits and to contribute to livelihood security, and
is receiving increasing attention as a sustainable land management option.
Whereas many studies highlight general positive environmental and
socio-economic effects of agroforestry systems, effects of the transition to
agroforestry practices have rarely been quantified and studied in detail, in
particular in Nepal. This paper analyses alterations of soil properties after
the adoption of agroforestry practices in a typical mid-hill region of Nepal.
Three agrosystems were COMPARED with a special focus on soil fertility: (i) a
mature, fully developed agroforestry system (AF); (ii) the predominant
conventional system (CS) characterized by mono-cropping; and (iii) a system that
has been in transition to AF for two years (TS). The results show significant
differences in soil pH, aluminium content, base saturation, electric
conductivity, organic matter and nitrogen content, and cation exchange capacity
between AF and CS soils, indicating a higher soil quality and more fertile soil
conditions in the AF soils. The contrasting soil quality has to be largely
attributed to the differing land management practices. After two years of
transition, the TS soil data already show a convergence towards the AF values
in several parameters. This study gives quantitative evidence that agroforestry
systems have the potential to significantly enhance soil quality and long-term
soil productivity, with positive effects appearing shortly after the conversion
from conventional monocropping systems.
Website: http://www.arjonline.org/agricultural-sciences/american-research-journal-of-agriculture/
Global consumption of
livestock products is increasing steadily due to human population growth,
poverty reduction and dietary changes raising the demand for already scarce
freshwater and land resources. Here, we analyze the changes associated with
direct and indirect use of freshwater and land for meat and milk production in
three production systems in Kenya between the 1980s and 2000s. We use two
resource use indicators, the water footprint (m3/year) and land footprint (ha),
to assess changes in freshwater and land use for cattle, goats, sheep and
camels in arid, semi-arid and humid production systems. We estimate actual
water and land use using Kenya-wide data for yields, feed composition and feed
conversion efficiencies. Our results show that the amounts of freshwater and
land resources used for production are determined mainly by production volumes
and feed conversion efficiencies. Total water and land footprints of milk
production increased for goats, sheep and camels but decreased by half for
cattle in arid and semi-arid production systems, in correspondence with similar
changes in the total numbers of each livestock species. Green water and grazing
land footprints dominated in all production systems due to the predominance of
indirect use of water to support forage production. The per unit meat footprint
for cattle increased significantly between the 1980s and 2000s in all
production systems, due to adverse trends in feed conversion efficiency, while
changes in the water and land footprints of other animal products were small,
due to modest changes in all influencing factors. In contrast, national average
footprints per unit of beef and milk show a modest decrease due to a relative
shift of production to the more resource-efficient humid production system.
Given the potential increase in demand for livestock products and limited
freshwater and land availability, feed conversion efficiencies should be
improved by rehabilitating degraded rangelands, adopting improved breeds and
using appropriate feed composition.
Website: http://www.arjonline.org/agricultural-sciences/american-research-journal-of-agriculture/
The method to estimate the
Gross Nitrogen Budget proposed by Eurostat and the OECD was developed under the
assumption of no changes in soil nitrogen stock, due to the lack of available
data. We estimated the national and regional nitrogen budgets of agriculture in
Turkey, calculated according to the recommended methodology at the level of
administrative regions. Results suggest that changes in soil nitrogen stocks
are likely for some regions. In such cases, the method warns that its estimated
indicators (gross nutrient surplus and nitrogen use efficiency (NUE)) are not
valid. We propose two different approaches to improve the Eurostat/OECD method,
based on assumptions of minimum and maximum NUE, and on regressing the N-input
and N-output relationship for regions without obvious soil nitrogen stock
changes. Our results show that both approaches give reasonable results for all
regions, including those for which the Eurostat/OECD method failed. The results
also suggest that soil nitrogen accumulates in some regions and depletes in
others. Results give a range of 6–93 kg N ha−1 yr−1 (mean 35 kg N ha−1 yr−1)
for the Gross Nitrogen Surplus, and a range of 49–82% (mean 62%) for the NUE.
Website: http://www.arjonline.org/agricultural-sciences/american-research-journal-of-agriculture/
Nearly one-half of New
Zealand’s ruminant livestock graze on hill country pastures where spatial
differences in soil conditions are highly variable and excretal deposition is
influenced by pasture production, animal grazing and resting behaviour that
impact the nitrous oxide (N2O) emission factor from excreta (EF3). New Zealand
currently uses country-specific EF3 values for urine and dung of 0.01 and
0.0025, respectively, to estimate direct N2O emissions from excreta. These
values have largely been developed from trials on flat pastoral land. The use of
the same EF3 for hill pasture with medium and steep slopes has been recognised
as a possible source of overestimation of N2O emissions in New Zealand. The
objectives of this study were to develop and describe an approach that takes
into account the effects of slope in estimating hill country N2O emissions from
the dung and urine of ruminant animals (sheep, beef cattle, and deer) across
different slope classes, and then COMPARE these estimates with current New
Zealand inventory estimates. We use New Zealand as a case study to determine
the direct N2O emissions between 1990 and 2012 from sheep, beef cattle and deer
excreta using updated estimates of EF3 for sloping land, the area of land in
different slope classes by region and farm type, and a nutrient transfer model
to allocate excretal-N to the different slope classes, and COMPARE the changes
between these hill pastures-specific and current inventory estimates. Our
findings are significant – the proposed new methodology using New Zealand
specific EFs calculated from a national series of hill country experiments
resulted in 52% lower N2O estimates relative to using current inventory
emission factors, for the period between 1990 and 2012 and reduces New
Zealand’s total national agricultural N2O greenhouse inventory estimates by
16%. The improved methodology is transparent, and complete, and has improved
accuracy of emission estimates. On this basis, the improved methodology of
estimating N2O emission is recommended for adoption where hill land grasslands
are grazed by sheep, beef cattle and deer.
Website: http://www.arjonline.org/agricultural-sciences/american-research-journal-of-agriculture/
Surface irrigated agriculture in arid and
semi-arid regions contributes to downstream environmental degradation. Changes
in irrigation system operational scenarios (ISOS) can represent an economic
alternative to reduce surface runoff impacts. At the same time the use of
vegetative filter strips (VFS) can have a positive impact on the ecological
health of rural landscapes by reducing erosion, improving water quality,
increasing biodiversity, and expanding wildlife habitat. The goal of this paper
is, using a combination of field data and mechanistic modeling results, to
evaluate and COMPARE the spatial effectiveness of improvements in ISOS and
introduction of VFS to reduce surface runoff pollution in the semi-arid/arid
furrow irrigation agroecosystem that exceeds current regulatory turbidity
limits (25 NTU). Five main factor interactions were studied: four soil textures,
two field slopes, three ISOS, six filter vegetation types, and ten filter
lengths. Slope and runoff volume were identified as the two main drivers of
sediment export from furrows. Shifting from current ISOS to less water
consumptive irrigation practices reduce runoff in addition to sediment delivery
to comply with environmental regulations. The implementation of 3–9 m
vegetative buffers on experimental parcels were found to mitigate sediment
delivery (greater than 90% sediment reduction) on tail drainage ditches but had
limited effect in the reduction of runoff flow that can transport other
dissolved pollutants. These findings were insensitive to filter vegetation
type. Thus, introduction of improved ISOS is desirable while VFS may be
targeted to specific hot spots within the irrigation district. This study shows
that the adoption of dense vegetation buffers in vulnerable semi-arid irrigated
regions can be effective to mitigate agricultural impacts and provide
environmental protection. However, it should not be adopted as an alternative
to proper on-site irrigation practices, rather as a complementary off-site
pollution control practice.
