environmental implication of intensive farming practices on north china plain
TRANSCRIPT
F
Environmental Implication of Intensive Farming Practices on North China Plain
Zhen Lin 1, Zhou Hailin 2 & Xie Gaodi 1 1 Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of
Sciences, Beijing 100101 , China; 2 The Administrative Center for China's Agenda 21, Beijing 100089, China
Abstract: The current pressure on production resources of North China Plain, such as land and water to feed the growing population, necessitates the assessment of the sustainability of farming practices. This study focuses on the sustainability of farming practices related to groundwater and soil fertility management. The assessment is based on selected site-specific key indicators and their established threshold limits. The current farming practices in the study area are clearly unsustainable. Only about 6% of the surveyed farm households practice sustainable farming. The study stresses that farming practice, which is economically sustainable, should not be promoted at the cost of environment. Holistic strategies need to be developed and implemented that aim at balanced use of inputs, which satisfY both productivity and environmental concerns. Key words: sustainability indicators, threshold values, farming practices, environmental implication
1 INTRODUCTION
Growing pressure on the land of North China Plain (NCP)
- a food bowl of rhe country, has made many of the
traditional farming practices increasingly difficult to sustain,
such as manuring, composting, mulching, legume-based
rotations, field levelling and fertilizing with mud from
rivers and canals. The pressure on the farmlands has also
led to a decrease in farm sizes and shortened fallow periods.
To cope with this pressure on the land and to maintain
its fertility, farmers in the area have, over the past three
decades, adopted high-yielding, external-input driven
production technologies from the western countries to
Corresponding auchor: Zhm Lin ([email protected])
complement and replace their traditional internal-input
based production technologies and practices. At present,
crop production in the area depends heavily on irrigation
with groundwater and the application of mineral fertilizers
and pesticides. In many parts of NCP, groundwater
exploitation exceeds groundwater recharge by a factor of
up to 1.5 meters (Liu et al ., 2001). Without the application
of mineral fertilizers the country cannot sustain the food
needs of the increasing population (Cheng and Han, 1992;
Lo and Xing, 1999). Excessive use of these main inputs
has led to land degradation in many parts of the area and
has also had adverse impacts on environment. The future
of the entire rural economy and the food security of the
people in the region will be determined by the sustainability
of agriculture and an effective management of natural
resources.
The sustainability of farming practices is a function of a
number of environmental, economic, and socio
institutional factors. To isolate the contribution to
Ch inese jou rnal of Population , Resources and Enviro nment 200; Vol. 3 No.3 11
sustainability made by these factors is extremely difficult
(Hassen, I 996; Pretty, I 996; Rigby and Caceres, 2001;
Wiren-Lehr, 200 I). There is, therefore, a need to devise
appropriate ways to measure sustainability, empirically
examine the sustainability of some well-defined cropping
systems, and to develop methods to measure externalities
that contribute to sustainability (Lynam and Herdt, 1989).
There is no universal recipe for sustainable farming practices.
The main factors that determine sustainability have to be
recognized. Quantifiable key indicators of these factors
need to be identified and measured (Rigby and Caceres,
200 I). If suitable specific indicators are selected, tt ts
possible to predict system trends (Pretty, 1996).
A common problem in the assessment of the sustainabiliry
of farming practices is the acquisition and integration of
suitable indicators that are spatially and temporally
significant. Most studies related to agricultural sustainabiliry
in the region have been confined to the exploitation of
soil and water resources (CAS, 2000). Few studies have
focused on water sutliciency and soil fertility analysis (CAS,
2000) and limited efforts have been made so far to assess
farming practices using location-specific indicators and
their threshold limits. Little is known about the effects
of particular fuming practices on environment.
For a typical agricultural area in NCP, this study attempts
to provide insight into the environmenral implications of
local farming practices. Location-specific indicators and
their identified threshold limits are used for the assessmenr.
Strategies for economically viable and conservation-orienred
crop production are recommended.
2 THE STUDY AREA
Ningjin County is located in the northeastern parr of
Dezhou District in Shandong Province in NCP. It is located
between 3T3i'and 3T50' North Latitude and 116"30'
to I I TOO' East Longitude. The county has 18 townships
with 856 villages. It has a total land area of 822 km2 and
a population of 440 000. The average population density
is 535 per km2.
The counry is a major food-production base of China,
with 80 percent of the total arable land under cereal
production. Most farms in the area are small and subsistence
based. The land is owned collectively and the per-capita
land area is about 0.10 ha. About ten different crops are
grown in the area. Winter wheat (Triticum sativum) and
summer maize (Zea mays) are the principal crops, which
occupy 75% of the total arable land, followed by cotton
( Gossypium) that occupies 18% of the total land area. The
remaining 7% of the land is used mainly for the cultivation
of vegetables such as chives (Allium schoengrasum), etc.
Less widely grown crops are peanut, sesame and sunflower.
Irrigation is widely practiced, with groundwater as the
only water source (IBNC, 2001).
Topographically the area is plain and homogeneous. The
average altitude is 15.4 meters above mean sea level. The
soils are very uniform; they are of alluvial origin and
dominantly loamy and moderately deep (SSODD, 1999).
The area has a continental monsoon climate (SBNC,
2000). It is characterized by an annual average temperature
of 12.3"C and annual precipitation of about 553 mm.
The precipitation is unevenly distributed. High rainfall
usually occurs in summer (April to September), accounting
for about 78 percent of the total annual precipitation. The
rainfall occurring between March and May accounts for
only I I o/o of the total annual rainfall. However, this is the
period most critical for crop-water demand. The rainfall
occurring from October to February has a share of only
I 0 percenr of the total rainfall, designating this period as
dry. The average evaporation is I ,319 mm, which is almost
double the annual rainfall. Declining and uneven
distribution of rainfall and high evaporation leads to an
increase in irrigation-water demand.
3 METHODOLOGY
3.1 Data collection and analysis methods
Data were collected from both secondary and primary
sources. Secondary data from statistical yearbooks and
documenrs were collected from relevanr governmenr
agencies. Primary data were collected through a household
survey, focus-group discussions (FGD), and inrerviews of
key informants, institutional surveys and field observations.
Data on current land-management practices included farming practices, amount of irrigation-water use, the use
of fertilizers and pesticides for the major crops (i.e., wheat, maize, cotton and chives), and farmers' perceptions and
knowledge of resource conservation. Four villages were
applied for the selection of household survey. A simple
random sampling method was adopted to select households for the survey. The household survey was conducted
between the first week of June and the last week of July 2002, and continued again from the first week of September until the last week of November 2001. Altogether, 270
households were interviewed.
The soil fertility status of wheat and maize fields has been
surveyed right after the harvest of maize in September.
Wheat and maize are cultivated in a cyclic way around the year. The analysis was performed on the plow layer
(i.e., 0-20 em). A total of 44 soil samples were analyzed for soil reaction (pH), soil organic matter (SOM) content,
and the contents of available nitrogen (N), phosphorus (P205) and potassium (K20). Fluctuations of the
groundwater table were analyzed using groundwater-table
data for the past 30 years obtained from the Water Survey Station of Dezhou District.
To investigate the environmental impact of current fertilizeruse practices, the nitrate contents of groundwater and
chives plants were also measured. The sample tube wells drawing water for irrigation from shallow groundwater were randomly selected. All wells have concrete casings for protection from contamination by surface water and
are fitted with electric or diesel-powered pumps. The tube
wells were pumped for about 3 minutes to remove any stagnant water before fresh water samples were collected.
A total of 20 samples were collected. All water samples were analyzed at the Irrigation Bureau of Dezhou District.
Similarly, nitrate residue in chives plants was surveyed through testing 20 chives plants taken from the fields. Samples were analyzed at the Epidemic Prevention Station of Dezhou District.
The ranking of the farmers perceptions of the environmental effects of water management was done by
weighting individual responses under different classes of occurrence as reflected by their ranks. The composite
picture of perception was obtained by computing an index
as shown below:
Index= (FIWI+ F2W2+ F3W3+ F4W4+ F5W5 + F6W6) IN (1)
Where Fl to F6 represent the frequency of responses ranked 'very high', 'high', 'medium', 'low', 'very low', and
disagreement cases, respectively. WI to W6 represent
corresponding weights applied to different ranked classes as mentioned before, specifically WI= 1.0, W2= 0.8, W3=
0.6, W4= 0.4, W5= 0.2, and W6= 0.0; and N = Sample
size = 270 Households.
3.2 Selection of indicators and threshold values
Indicators have to be based on an understanding of the pressures on the environment and the processes through which human activity induces environmental change (Crabtree and Bayfield, 1998). To detect and monitor
changes and determine trends in improvement or deterioration in groundwater and soil quality in the study
Chinese Journal of Population, Resources and Environmenr 2005 Vol. 3 No.3 13
area, key indicators need to be selected and their threshold
values established. For the study, the indicators and their
rankings were identified from published research (Zhang,
1995; Zhang, eta!., 1998; Hu, eta!., 1996) and information
given by farmers. The selected indicators and their threshold
values are crop and site-specific. These indicators cover
environmental aspects, such as depth to groundwater table,
water use efficiency (WUE), soil-quality status as
represented by soil pH, SOM content, N, P205 and 1<20
content, and nitrate (N03-) concentration in groundwater
and chives plants (Table I). The selection of these indicators
is based on the following two criteria: (I) Significance of
the indicators for the study area. The selected indicators
cover the major farming practices. (2) Practical applicability
of the indicators selected. The indicators selected are all
location specific; data for the measurement of each indicator
and the threshold values for indicator assessment are
available at the local level. The selection of the indicators
has been done in cooperation with local experts and the
farmers.
The implications and assumptions of the threshold values
for the selected indicators in relation to sustainability are:
e"Very good" and "good" mean that there is no indication
of a problem or problematic trend.
e"Fair" is the borderline condition for sustainability.
Some actions are needed to address the problem or more
detailed information should be sought to suggest how to
stop a decline in the condition.
Table 1. Threshold values for selected indicators
e"Poor" and "very poor" mean that there is indication
of a problem or problematic trend. Urgent actions are
needed to improve the condition.
4 RESULTS AND DISCUSSIONS
4.1 Groundwater management practices
In surveyed villages, groundwater is the only source of
irrigation. Each household has equal access to and share
of the groundwater resources. All irrigation systems in the
county are small-scale. They are constructed by the farmers
themselves using locally available materials and skills. The
field survey showed that well digging is not planned.
According to their felt needs, they decide where to locate
the wells and how many wells to dig. They also use the
water at their own discretion. The farmers prefer to have
their wells very close to their plots. This has led to an
increase in the number of wells in the area, from 5 872
in 1978 to I 0,180 in 2000, with an average density of 20 wells per km2. On average, each ten households own one
well, to which several pumps for water lifting may be
connected. The average distance from the wells to the field
is 120 meters, with a range between I to 500 meters.
Water is conveyed to the fields by plastic pipes. All farmers
have adopted basin irrigation. Since no fee is charged for
the groundwater, the farmers pump as much groundwater
as possible in order to meet their irrigation needs. The
• .\,·r fin)lul'iog< "" •l>ik 1/w '"t!' dl<' rlfllllll!illrd /~1 f/ui'IO_'!,t'lik s111l> ll'ith •llllil.tr 11'.\'1/tn' d<ro.f.• r/>1' .•i1111flingji;mu· 111 the _,·,unp/ing .•it c.• ofrf,j_, .•lilt()' .
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14 Chinoc ]ourn.d of PopuLuion, Rnour~_t', .wd FnvironnH:nt 200') \'ol. j l'\o .. ~
quantity of groundwater actually used for irrigation is
significanrly higher (AN OVA rest, p<O.OO I) than the
recommended quantity for all the crops under study,
regardless of farm size and varieties of crops. For instance,
the recommended quantity of water for one irrigation of
wheat, maize, cotton and chives is 600-750, 525-675,
600-750 and 750-900 m-'/ha, respectively, while the actual
quantity of water used is 975, 94 5, I 005 and I 065 m3/ha,
respectively. Overuse of groundwater is encouraged by
the low irrigation cost. Groundwater charges to farmers
cover only the costs of pumping and distribution of water.
There is no "capital" charge for the water itself. Therefore,
in order to ensure crop production in a small landholding,
farmers apply as much water as possible to irrigate the
land. However, the water use efficiency (WUE) is very
low. WUE of wheat, maize and cotton is 1.26, 1.45 and
0.60 kg/m·\ respectively, which is classified as poor to very
poor (Table I).
4.2 Environmental implications of groundwater
management practices
During the field survey, farmers were asked about their
perceptions of groundwater use practices. The composite
picture of perception was obtained by computing an index
(see Eq. [I]). 'Declining groundwater table' is featured
as the most important adverse environmental effects caused
by current water management practices, followed by
'declining groundwater quality', 'increasing irrigation cost',
and 'increase soil salinity', these problems are ranked as
important dTecrs, followed by 'compacted or hardened
soil', 'increasing land subsidence' and 'creates water logging'
(Table 2). Evidence from both primary and secondary
sources has been used to support farmers' perceptions.
The statement 'declining groundwater table' has been
substantiated by farmers' observation and the trend analyses
of rhe groundwater table in the study area; 97 percent of
the farmers observed a decline of the groundwater table
by an average of I 0 m over recent years. One tenth of rhe
wells rend to dry up temporarily during summer season,
a few of these wells have been abandoned altogether.
According to groundwater-observation data from 50
shallow wells in the county, the average depth of the
groundwater table has fallen from 12.36 m in 1970 to
7.73 m in 2000, i.e., an annual water table decline of
0.21m.
Table 2 Ranking of farmers' perceptions of the adverse
environmental effects of groundwater use
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fUJJ-O..!O..ot't'l"\lo/1'
O . .ll-0.·!0=/oll' 0.·11 O.(J()_,J/laliulll
O.M-fUW=I't.'!.l' 0.8/- J.(}().o
The depth of the water table varies according to the season.
It remains relatively stable (i.e., between 8.66 m and 8.72
m) between November and February, as there is nor much
demand for irrigation during that period. However, it
starts to decline sharply in April and reaches its lowest
level in May at 6.37m. These are rhe peak months for the
irrigation of winter wheat.
The roral dissolved salt content has been used as an
indicator of groundwater quality (Kandiah, 1990). For
irrigation, salt concentration should be less than 0.5 g/1
(CAS, 2000). However, the salt content of groundwater
in the area is 0.65 to 1.40 g/1. Crops irrigated with this
water should be salt tolerant, and a drainage system should
be available to EKilirare leaching. The dominant irrigated
crops are wheat (moderately salt tolerant) and maize
(moderately salt sensitive). The field survey showed that
maize yields decline. This has also been observed by the
farmers, who even term the groundwater "dangerous
water". Increasing soil salinity is also evident from white
parches that can be observed after irrigation. Irrigation
cost refers to both time and money. Over-exploitation of
groundwater results in a progressive decline in yields due
to an increase in suction lift and the drying-up of wells.
Well yields have decreased from an average 35 m·1/hr in
1965 to I 0 m-'/hr in 2000. Correspondingly, time spent
in pumping water for one hectare of cropland increased
from 22 hours in 1965 to I 05 hours in 2000. These
conditions have led to increased consumption of diesel,
electricity and labor, and hence in the overall cost of water
lifting.
Farmers' awareness of the shortage of groundwater plays
an important role in their management behavior. The
majority of the farmers (82%), regardless of the villages
and the kinds of crops cultivated, agreed that groundwater
should be used efficiently. However, they did not realize
the actual scarcity of groundwater. Their perception was
that groundwater is renewable and inexhaustible. This
perception has encouraged them to use groundwater more
intensively for short-term benefits. The farmers consider
groundwater as a free gift and use it according to their
own demand and benefit. They have not been made aware
that their water use is depleting the groundwater resources
of the area.
4.3 Soil-fertility management practices
4.3.1 Soil-fertility management practices
The farmers in the area use fertilizers very intensively to
maximize their yields. The major sources of plant nutrients
are mineral fertilizers followed by farmyard manure (FYM)
and crop residues. The mineral fertilizers used are mainly
nitrogen (N), phosphate (P205), and potassium (K20),
which are available everywhere in the area and the farmers
have the cash to purchase these fertilizers. Usually, the
top-dressing method is used for mineral fertilizer
application. The main source of FYM is the livestock
reared by households, but some FYM is also purchased.
The FYM is applied to the field during the land preparation.
The crop residue is mainly the wheat straw that is left in
the field for the following maize cultivation. Maize residues
are rarely used for the following wheat crop.
Compared with the application rates recommended by
the extension service, FYM and K20 are used in insufficient
amounts, while N and P205 are over-applied. Nitrogen
is significantly overused for all the crops studied. The
recommended application rates of N for wheat, maize,
cotton and chives are 210-255, 165-210, 195-240, and
600-750 kg/ha respectively, while the actual rates applied
by the farmers are 375, 240, 360, and 1035 kg/ha,
respectively.
16 Chinese Journal of Population, Resources and Environment 2005 VoL 3 No.3
The study revealed that the majority of farmers (65%)
prefer to use a combination of organic and mineral
fertilizers, because of the positive effect of manure on
structure, aeration and water holding capacity of the soil.
The application of FYM by farmers is limited by its
inadequate availability. The survey revealed that the farmers
do not know how to use mineral fertilizers properly. They
are not guided by the extension service in appropriate and
balanced use of fertilizers based on existing soil fertility
conditions and the nutrient requirements of the crops.
They normally apply fertilizers in together with irrigation,
increasing the leaching of nutrients into the groundwater.
Also, easy access to input markets and low prices of inputs
encourage the farmers to apply more mineral fertilizers
than actually required, particularly nitrogen and
phosphorus.
4.3.2 Nutrient status of the soil
A simple nutrient balance for the main crops grown in
the area reveals the approximate nutrient status of the
soils. The nutrient balance W<!S computed as the difference
berween inputs applied and extracted by the crop using
conversion factors developed for the area by Fan and Fen
(1999) (Table3).
Table 3 shows that there is generally a positive net balance
ofN and P205 in the soil. The highest quantities of these
nutrients were found in chives fields, followed by cotton,
wheat, and maize fields. These nutrients remain in the soil
and may be subject to leaching before the following crop
is established. Under these conditions, the application of
fertilizers is probably not economical, particularly for the
Table 3 Nutrient balance in the soil for the main crops
"Fan and Fen, 1999. Source: Fi~ld survey, 2002.
farmers who have already high to very high levels of these nutrients in their soils. However -with the exception of the chives fields-, the 1<20 balance is negative. This fact points to a possible depletion of 1<20 and thus the risk unbalanced plant nutrition. This result concurs with the observation reported before that 1<20 fertilizers are usually applied below the recommended rates. Similar results were found by studies conducted in other areas of the NCP (Xu, 2000; Huang et al., 2000).
Soil fertility as reflected by the selected indicators (i.e., SOM, N, P205, and 1<20) has improved over the past 20 years. From 1982 to 1999, SOM content increased from 0.85 to 1.16%, N content from 64 to 70 mg/kg, P205 from 7 to 15 mg/kg, and 1<20 from 108 to 123 mg/kg (SSODD, 1999). Soil pH in the study area has been assessed as fair (i.e., moderately alkaline) (Table 4), which is considered the threshold value for sustainability. Further improvement in soil pH is required for increasing production and enhancing soil fertility.
Soil organic matter (SOM) has been widely promoted as a key indicator of soil quality, particularly for agricultural soils (Nortcliff, 2002). The majority (85%) of the farms have good or very good soil organic matter levels. This can most probably be attributed to the massive return of crop residues to the fields and the increasing application of FYM. However, compared to the recommendations by the extension service, FYM applications are still insufficient.
The soil tests revealed that the average N levels were fair, covering about 60% of the sampled households; P205 levels were generally rated good, with 85% of the households in the good and very good range. Potassium
Table 4. Soil-fertility status of the farmland for the sampled
households
Bas~d on Table 1. Figures in parmth~m a" pnrmtag~s ofsampkd households. Sourct: Field survey. 2002.
levels were generally fair, with about 50% of the households. According to the selected key indicators, therefore, the current soil-management practices do not lead to nutrient depletion and soil degradation. However, there is still scope for the improvement of soil-fertility management practices, especially in relation to long-term soil-quality maintenance based on adequate organic-matter application.
4.3.3 Environmental implications of soil fertility management practices The study found that excessive use of fertilizers can cause groundwater contamination and lead to high nitrate residue in chives. Of20 groundwater samples tested, 16 had an average nitrate concentration of 115 mg/l, which is significantly higher than the threshold value of 50 mg/l. There is a significant positive relationship between nitrogen application and nitrate concentration in the groundwater (r=0.701 **, p<0.01), demonstrating that the groundwater is contaminated by nitrogen fertilizers. Also in chives, the nitrate concentration exceeds the maximum allowable level for human consumption. The significant positive correlation between nitrogen application rates and nitrate concentration (r=0.855**, p<O.Ol) indicates that over-application of nitrogen is the main cause of the contamination of chives.
The farmers in the area have not yet realized this critical situation. They believe that water contamination is only related to surface water. In their perception, the groundwater is very clean. None of the farmers are aware of the linkage between fertilizer application and nitrogen concentration in the plants. Consequently, they are not aware of the potential hazards for human health.
4.4 Pest and disease management
Pests and diseases are serious problems, which the farmers face in the area. Therefore, all farmers use pesticides, which are cheap and freely available. To be sure of the chemicals' effects, they usually apply high doses. The average application rates of pesticides are two to three times the recommended dosages. The farmers express increasing concern of human health and environmental contamination by
Chinese Journal of Populacion, Resources and Environment 2005 Vol. 3 No.3 17
Table 5 Summary of indicators and implications for sustainability
*Refl-r to lflb!e I for threshold Z'llltm ,md tmplmatonJ fOr _>ushJtntJbi!ity of respective indicators.
overuse and improper handling of pesticides. However,
they still prefer to use high doses because they still consider
the beneficial effects greater than the harmful effects. The
survey revealed that the perceived negative effects of
pesticides are headache, nausea, stomach pain, skin rash,
and the reduction of the number of natural predators in
the fields, such as frogs and cicada. Chives growers tend
to use higher doses of pesticides than others, and the
reported occurrence of health problems is also higher.
The study revealed that, out of nine initially selected
environmental indicators, five satisfied the minimum
condition for sustainability, i.e., soil pH, SOM content,
N, P205 and K20 content of the soil. The indicators that
could not meet sustainability conditions were the depth
to groundwater table, WUE, and the concentration of
nitrate in the groundwater and the chives plants. These
particular soil characteristics exceed the thresholds levels
or safe minimum standards, which were defined as fair
in this study (Table 5).
5 SALIENT FEATURES OF SUSTAINABLE AND
NON-SUSTAINABLE FARMERS
The study clearly revealed that groundwater, fertilizers
1 8 Chinese Journal of Popul.uion, Resources and Environment 2005 Vol. 3 No.3
and pesticides are the main inputs used in the farming
system, and these are also the major causes of problems
for the water and soil resources and human health. Balanced
and integrated use of inputs is considered as an appropriate
way to assure long-term productivity with sufficient
economic returns. Therefore, recommended levels of input
use based on scientific research have been proposed to the
farmers.
Based on the assumption that recommended input
application rates practices enable sustainable farming, two
types of farmers were identified, i.e., those who follow
recommended input-application rates were classified as
sustainable farmers' (SFs) and those who do not follow
the recommendations were classified as 'non-sustainable
farmers' (NSFs). Taking wheat-maize farmers as an example,
only 16 farmers (6%) of256 farmers could be classified
as 'sustainable' (Table 6).
Table 6 shows of the 12 indicators that were examined,
six show statistically significant differences between SFs
from NSFs. SFs are younger than NSFs; they are probably
more active in learning and acquiring new knowledge and
technology, and more open to accept innovations in their
farms than the older farmers. They are also likely to be
Table 6. Salient.features of 'sustainable' and 'non-sustainable'
farmers
'P<0.05 . .. P<O.OJ (t- Tm).
Note: The indicators used for the classification of *ustainab/e'"and '"on-sustainable *formers are
groundwater use, nitrogm use and pesticide used compared with the recommmded quantities. Only
wheat and mazu rotational croppingfonners were UJed for analysis. Souru: Field survry. 2002.
more aware of the environmental effects of excessive input
use. SFs input-application rates are within the limits of
the recommended rates, i.e., lower than the rates applied
by NFSs. Soil K20 levels are higher in the fields of SFs
(98 mg/kg) than those of NSFs (86 mg/kg), implying a
better balance between the nutrients in SFs fields. SFs use
high quantities of FYM, i.e., nearly 10,000 kg/ha more
than NSFs.
6 CONCLUSIONS
The objective of this research was to assess the sustainability
of farming practices in the light of its environmental
implications. The key indicators used are highly specific
to the crops and location of the study. Feedback from the
farmers, extension workers, local and regional government
decision-makers and researchers confirmed the soundness
of these indicators.
Concerning environmental sustainability, current irrigation
practices deteriorate and deplete the groundwater resources
and increase irrigation cost. The combination of ignorant
attitudes of farmers related to the environmental effects
of their water-use practices, low overall water-use efficiencies.
In this scenario, irrigation-based crop production in the
area is unlikely to sustain for a long period. The dependence
on pesticides and their overuse and improper handling has induced serious environmental and human health
hazards. Increased use of both organic and mineral fertilizers
over the years improved soil fertility. The soil status in
general is within the borderline for sustainability implying
that the current soil-management practices do not
deteriorate the soil resources. However, overuse of mineral
fertilizers, particularly nitrogen, contaminates the
groundwater and leads to excessive nitrate levels in crops,
thus making this practice environmentally unsustainable.
Some scholars argue that organic farming or low-external
input agriculture is sustainable while high-external input
agriculture is not sustainable (Tisdell, 1996; MacNaeidhee
and Culleton, 2000; Rossi and Nota, 2000). However,
Dahal (1996) and Rahman (1998) found that organic
farming without proper use of additional mineral fertilizers
and pesticides leads to a negative nutrient balance in the
soil, with negative impacts on environmental and
economical sustainability. On the other hand, exclusive
emphasis on yields and farm income through intensive
use of mineral fertilizers will cause environmental
degradation, also threatening the sustainability of farming
practices (Altieri, 1992). China has successfully sustained
the productivity level of wheat and rice for over 100 years
by meeting 50% of the nitrogen requirement from organic
sources. Therefore, balanced and integrated use of mineral
fertilizers together with organic fertilizers -on the basis of
soil tests- promise long-term productivity with sufficient
economic returns. For the maintenance of soil fertility on
a sustainable basis in intensively cropped areas, greater
emphasis needs to be placed on residue management and
legumes as intercrops.
According to Smith and McDonale (1998) and Wiren
Lehr (2001), sustainability in general is vague when both
outputs and inputs increase. However, in the study area
-which is characterized by simultaneous increases in both,
input and output levels-, the unsustainability of farming
practices could be clearly revealed using crop and site
specific indicators and threshold values.
There are a number of limitations in terms of the way the
indicators are used. Some indicators represent various
dimensions of sustainability at the same time and may, in turn, be affected by other indicators, either positively
or negatively. For the selection of key indicators, it is
Chinese Journal of Population, Resources and Environmenr 2005 Vol. 3 No.3 19
therefore very important to ensure location and site
specificity.
Acknowledgement
The research is under the auspice of the National Natural
Science Foundation of China (C44300) and national key
project for basic research on Agricultural Environment
(2002CB 111506). The financial support for the study
from the Asian Institute ofTechnology (AIT), and the
Regional Office of the Food and Agriculture Organization
(FAO) for the Asia-Pacific Region in Bangkok is greatly
acknowledged.
20 Chinese Journal of Populalion, Resources and Environment 2005 Vol. 3 No.3