Innovations in agronomy for food legumes. A review - HAL-Inria

21 Pages·2016·1.27 MB·English

Innovations in agronomy for food legumes. A review
Kadambot Siddique, Johansen, Neil Turner, Jeuffroy, Hashem, Sakar, Gan,
Salem Alghamdi
To cite this version:
KadambotSiddique,Johansen,NeilTurner,Jeuffroy,Hashem,etal.. Innovationsinagronomyforfood
legumes. A review. Agronomy for Sustainable Development, 2012, 32 (1), pp.45-64. ￿10.1007/s13593-
011-0021-5￿. ￿hal-00930490￿
HAL Id: hal-00930490
https://hal.science/hal-00930490
Submitted on 1 Jan 2012
HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est
archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents
entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non,
lished or not. The documents may come from émanant des établissements d’enseignement et de
teaching and research institutions in France or recherche français ou étrangers, des laboratoires
abroad, or from public or private research centers. publics ou privés.
Copyright
Agron.Sustain.Dev.(2012)32:45–64
DOI10.1007/s13593-011-0021-5
REVIEWARTICLE
Innovations in agronomy for food legumes. A review
Kadambot H. M. Siddique&Chris Johansen&
Neil C. Turner&Marie-Hélène Jeuffroy&
Abul Hashem&Dogan Sakar&Yantai Gan&
Salem S. Alghamdi
Accepted:8October2010/Publishedonline:18March2011
#INRAandSpringerScience+BusinessMediaB.V.2011
Abstract Although there is increasing awareness of the smallholder farming in developing countries, production
importance of food legumes in human, animal and soil trends have mostly been static or have declined over the
health, adoption of improved production technologies for past decade despite the existence of technology that should
foodlegumecropsisnotproceedingatthesamepaceasfor permit higher and more stable yields. Ability to reverse
cereal crops. Over the previous decade, the only food negative trends is jeopardized by climate change as food
legumes to have shown significant production increases legumesaremostlygrownrainfedandarebeingexposedto
havebeenchickpea,lentilandfababeaninNorthAmerica, increasingly variable and extreme weather. This review
chickpea in Australia, and faba bean in Europe. In examines recent innovations in cultivation technology for
the major food legumes—chickpea, lentil, dry pea, faba
:
K.H.M.Siddique(*) N.C.Turner bean, lupin, common bean, mung bean, black gram,
TheUWAInstituteofAgriculture, cowpea, and pigeonpea—and explores constraints to their
TheUniversityofWesternAustralia,
adoption, particularly by resource-poor smallholder farm-
35StirlingHighway,
Crawley,WA6009,Australia ers. Conservation agriculture, involving minimum soil
e-mail:[email protected] disturbance, maximum soil cover, and diverse rotations,
: : has contributed to sustainable cropping system production
K.H.M.Siddique C.Johansen N.C.Turner
inlarge-scalecommercialfarmingsystemsintheAmericas,
CentreforLegumesinMediterraneanAgriculture,
FacultyofNaturalandAgriculturalSciences, Europe, Australia, and Turkey. Temperate food legumes
TheUniversityofWesternAustralia, have been incorporated into such systems. Adoption of
35StirlingHighway,
conservation agriculture is only just beginning for small-
Crawley,WA6009,Australia
holder farming in Asia and Africa, catalyzed by the
M.-H.Jeuffroy development of low-cost implementssuitable for minimum
UMRAgronomieINRA/AgroParisTech, tillage. Water use efficiency improves with conservation
BP01,78850Thiverval-Grignon,France
agriculture as it allows for earlier planting, reduced soil
evaporation,betterweedmanagement,andincreasedaccess
A.Hashem
DepartmentofAgricultureandFoodWA, to nutrients. Ecosystem-based approaches to plant nutrition
P.O.Box483,Lot12,YorkRoad, are evolving which place more reliance on accessing
Northam,WA6401,Australia
organic and mineral reservoirs than in replenishing the
immediately available pool with chemical fertilizers, lead-
D.Sakar
DicleUniversityFacultyofAgriculture, ingtoenhancednutrientuseefficiencyofcroppingsystems.
Diyarbakr,Turkey Ecosystem-based approaches are also being applied to
management of weeds, diseases, and insect pests of food
Y.Gan
legumes, again with decreased reliance on synthetic
AgricultureandAgri-FoodCanada,
Gate#3,AirportRoadE., chemicals. In achieving sustainable agricultural production
SwiftCurrent,SKS9H3X2,Canada systems, there is increasing realization of the need to move
: towards the tenets of organic agriculture, as exemplified in
K.H.M.Siddique S.S.Alghamdi
conservation agriculture and ecosystem-based approaches
CollegeofFoodandAgriculturalSciences,KingSaudUniversity,
P.O.Box2460,Riyadh11451,SaudiArabia to plant nutrition and pest management. This does not
46 Siddiqueetal.
necessarily imply a desire to qualify for organic product and agronomic improvements should proceed in a comple-
certificationbutmorearealizationoftheneedforsustainable mentarymanner,asanewgenotypeoftenrequiresachange
agriculture.Themovementtowardsconservationandorganic in cultivation practice to achieve potential yields. This
agricultureencouragesgreaterinclusionoffoodlegumes,and paper examines some of the more recent, since the turn of
legumes generally, in cropping systems. Unfortunately, how- the century, innovations in agronomic practices that are
ever, technology transfer toresource-poor farming situations, contributing to, or potentially can contribute to, increased
where most food legumes are produced, remains a major yieldsandproductionofthemajorfoodlegumes.
bottleneck to meeting global demand. More participatory In this review, we address the following major food
approaches to technology development, testing, and dissemi- legumes:chickpea(CicerarietinumL.),lentil(Lensculinaris
nationarerequiredthanhithertopracticed.Itissuggestedthat Medicum),drypea(PisumsativumL.),fababean(Viciafaba
this process could be enhanced by better focusing on major L.), lupin (Lupinus spp.), common bean (Phaseolus vulgaris
constraintswithinthevalueadditionchainforfoodlegumes. L.), mung bean [Vigna radiata (L.) Wilczek], black gram
[Vigna mungo (L.) Hepper], cowpea (Vigna unguiculata L.),
Keywords Legume area trends.Climate change. and pigeonpea (Cajanus cajan L.). These crops are grown
Conservation agriculture.Smallholder farming.Water use across a wide range of farming systems, from subsistence
efficiency.Nutrient use efficiency.Weeds.Integrated agriculture to sophisticated commercial production systems.
disease management.Integrated crop management We firstly examine to what extent any recent increases in
yield and production of food legumes in major producing
Contents countries over the past decade can be attributed to imple-
mentation of improved agronomy. Concepts and practice of
1.Introduction.................................2
conservation agriculture, involving trends towards minimum
2.Recenttrendsinarea,yieldandproduction.........2
tillage, have advanced considerably in recent years, and
3.Copingwithclimatechange....................4
legumes are considered important components of such
4.Roleoflegumesinconservationagriculture........5
systems. Ever-increasing degradation of agricultural lands
5.Increasingwaterandnutrientuseefficiency........7
worldwideandclimatechangearedemandingmajorchanges
6.Weed,diseaseandpestmanagement.............11
intraditionalagronomicpractices.Ofparticularimportancein
7.Integratedcropmanagement...................13
this regard is the formulation of strategies to improve water
8.Improved legume agronomy for resource-poor
and nutrient use efficiency. Rapidly changing incidence and
farmers.. .... .... ..... .... .... ..... .... .15
manifestation of weed, disease, and pest problems require
9.Conclusion...................................16
changes in traditional agronomic practices. There is increas-
10.References................................17
ing realization of the need to implement more ecologically
based practices and at least move in the direction of organic
agriculture, in which legumes have a major role. Farmer
1 Introduction implementation of improved agronomic practices requires
integration of many interacting components; there is a need
There is increasing awareness of the importance of food for translation of findings from component-based research
legumes in improving the health of humans (Tharanathan into integrated crop management packages. Finally, we
and Mahadevamma 2003), production of farm animals examine reasons behind slow adoption of agronomic inno-
(Gatel 1994), the soil in which legumes grow (Biederbeck vations by smallholder, resource-poor cultivators of food
et al. 2005), and in mitigating greenhouse gases (Lemke et legumes and suggest means of hastening adoption.
al. 2007). Nevertheless, food legumes remain poor cousins
to the major cereal crops (rice, wheat, maize) due to the
ever-increasing global demand for cereals from burgeoning 2 Recent trends in area, yield, and production
humanpopulations.Prioritiesforcultivationandresearchin
foodlegumesremainsecondarytothoseforcerealsinmost Significantincreasesinareasowntofoodlegumesintherecent
cropping systems. Contributing to this is the relatively decadehaveoccurredmainlyincountrieswheretheyaregrown
greater sensitivity of food legumes to various abiotic and on a commercial scale on large land holdings, as in North
biotic stresses than cereals,increasing their cultivation risk, AmericaandAustralia(FAO2010;Fig.1).Therehasbeenlittle
and their lower grain yield potential compared with change and sometimes a decline in area where smallholder
competing cereal crops. While genetic improvement is subsistenceagriculturepredominates.Thisisdespiteincreasing
required to address these problems, agronomic improve- local and global demand for each of these commodities.
ments can significantly contribute to closing the yield gap India isthemajor producerof chickpea, where there has
induced by various stresses. Practically, however, genetic been a gradual recovery in production area after a slump at
Innovationsinagronomyforfoodlegumes 47
Area (m ha) Area (m ha)
15 a) Chickpea 5 b) Lentil
World 4 World
10
Asia 3 Asia
India 2
5 India
Pakistan 1 Americas
Turkey
Turkey
0 0
7 c) Dry Peas 1.5 d) Lupins
6
World
5
1.0
4
World
3 Europe
Asia
0.5
2
Australia
1 Americas
India
0 0.0
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
Fig.1 Trendsinareassowntoachickpea,blentil,cdrypeas,anddlupinsinmajorproducingcountriesandregionsinthepreviousdecade.
Valuesfor“Asia”includethoseforIndia,Pakistan,andTurkey.Source:FAO(2010)
thebeginningofthedecade(Fig.1a).Thiscanbeprimarily in Bangladesh mainly due to adoption of varieties with
attributed to the expansion of chickpea in Peninsular India increasedresistancetothemajordisease,stemphyliumblight
withtheadoptionofshortdurationvarieties(Satyanarayana (Aw-Hassanetal.2009).Theareasowntolentilhasdeclined
et al. 2001). There has been a gradually declining trend in in Turkey (Fig. 1b), but production has been compensated
Turkey,theothermajorproducerinAsia(Fig.1a).Thearea for by an increasing yield trend (FAO 2010). This can be
planted to chickpea in North America and Australia attributedtothespreadofcertifiedseedofhighyieldingand
declined from 2000 to 2005 (FAO 2010), mainly due to early maturing lentil cultivars with good quality character-
outbreaksofascochytablight.However,sincethenthearea istics especially in the south-eastern region of Turkey.
sownintheselocationshasrecovered,duetobetterdisease TheareaofdrypeacultivationhasincreasedonlyinNorth
managementviatheintroductionofvarietieswithenhanced America, especially Saskatchewan, Canada (Fig. 1c). Rota-
host plant resistance (Chandirasekaran et al. 2009), and tions of the shallow-rooting dry pea (Liu et al. 2010) with
agronomic measures such as more effective fungicidal cereals and oilseeds have improved resource use efficiency
spraying (Armstrong-Cho et al. 2008) and plant canopy (Miller et al. 2003), increased yield and quality of
manipulation and management (Gan et al. 2006, 2009). As subsequentcrops(Ganetal.2003),andenhancedbiological
chickpeaispredominantlyarainfedcrop,therearenoclear attributesofthesoil(Biederbecketal.2005).Theareasown
trends in yields (FAO 2010) which fluctuate from year to to faba bean has increased in both North America and
year according to seasonal rainfall. EuropebutdeclinedinAsia(FAO2010).Therearenoclear
Theonlyappreciableincreasesinareasowntolentilover yield trends with either dry pea or faba bean (FAO 2010);
thepastdecadehavebeeninNorthAmerica(Fig.1b), which there is considerable year-to-year variation in yield attribut-
has been largely driven by the increased incentives of able to rainfall and foliar disease. Area and production of
adopting diversified cropping systems in the northern Great lupin in Australia, by far the major producer of lupin grain,
Plains(Ganetal.2010).Areassowntolentilhaveremained hasdeclinedmarkedlyoverthepastdecade(Fig.1d).Thisis
steadyinIndiaandNepal,buthavedeclinedinPakistanand mainly due to declining market demand and increasing
Bangladesh (FAO 2010; Fig. 1b). There has also been a herbicide tolerance of weeds in lupin crops in Australia
decreasing yield trend in Pakistan, but yields are increasing (Sweetingham and Kingwell 2008).
48 Siddiqueetal.
Globally,thearea sowntobeans hasincreasedprimarily legumes are grown; in tropical regions rainfall may
due to increases in both Africa and Asia (FAO 2010). In increase, but this is likely to arise from extreme rainfall
Africa, increasing areas of common bean are being sown events and more frequent periods of within-season drought
while areas under mung bean and black gram have (Christensen et al. 2007). While specific temperature
increased in South and East Asia. These increases are increases and frequency of extreme temperatures and
attributed mainly to the availability of improved varie- droughts are locally variable, the general consensus is that
ties, such as shorter duration and more disease-resistant crops and cropping systems should be more flexible and,
mung bean (Shanmugasundaram 2006), rather than any except for regions of North America, northern Europe, and
improvements in agronomic management. Africa remains northern Asia where temperatures are below the optimum
the major producer of cowpea, but there has been no for crop growth, changes in climate are likely to decrease
appreciable increase in area sown or yield over the last rather than increase yields. For example, Cooper et al.
decade (FAO 2010). In contrast, cowpea area and yields (2009) used a modeling approach to predict that a
have increased in Asia, probably as a result of availability temperature rise of 3°C will reduce the current median
of improved varieties (Singh et al. 2002). India is the yield of peanuts in Zimbabwe by 33% and pigeonpea in
major producer of pigeonpea, but area and yields have Kenya by 19%, largely as a result of shorter growing
remained relatively stable over the past decade (FAO periods and earlier maturity at higher temperatures. The
2010). Myanmar appears to be the only country where decrease in time to maturity results in water left in the
pigeonpea area and yields have increased. This has been profile such that adjusting the phenology of plants is
mainly driven by the export market to neighboring India suggested as one mechanism to manage climate change
(Thaung and Choi 2008). (Cooper et al. 2009; Vadez et al. 2011). Modeling a 10%
Thisbriefoverviewofrecentyieldandproductiontrends decrease in daily rainfall in groundnut reduced yields by
has found little evidence of agronomic improvements less than 9% (Cooper et al. 2009), much less than the
leading to upward trends. The only examples are chickpea, decrease in median yield for a 3°C rise in temperature, but
lentil, and faba bean in North America, chickpea in this does not take into account the predicted changes in
Australia, and faba bean in Europe, where a combination rainfall distribution and crop failures.
of genetic and agronomic improvement factors can be While the Intergovernmental Panel on Climate Change
attributed to the increases. For grain legumes grown under (Christensen et al. 2007) predicted that extremes of high
smallholder, near-subsistence farming conditions, it is temperature and rainfall and the length of dry spells are
difficult to ascribe any specific agronomic improvement to likely toincreaseoverthenext90years,thepanel wasless
significant and persistent increases in area sown or yield. able to predict the degree and extent of such extreme
Any increasing trends noted are mainly attributable to the events.Theabilityoffoodlegumestoadapttothepredicted
availability of improved varieties or economic factors extremesoftemperatureandrainfall islargelyunknown.In
driving production. This is disappointing considering the a recent study, Prasad et al. (2006) showed that when air
quantum of agronomicresearch on food legumes undertak- temperature increased from 36/26°C to 40/30°C, panicle
en for resource-constrained, smallholder conditions and the emergence in sorghum was delayed by more than 20 days,
increasing demand for legume grain. This raises questions paniclesweresmaller and less branched, and seed set, seed
as to appropriate targeting of the research and whether the size, and growth rate of seeds was markedly reduced. The
relevant information is indeed reaching farmers. This is reduced seed set resulted from poor pollen production and
discussed in more detail later in this review. viability. The reductions were slightly greater when the
carbon dioxide level was doubled from 350 μmol mol−1 to
the predicted 700 μmol mol−1. A drastic reduction in seed
3 Coping with climate change set at high temperatures has also been observed in rice.
Exposing rice to 34°C for 1 h at peak anthesis around
On-going climate change poses an increasing threat to 1100hcausedsterility (Jagadish etal.2007),andexposing
production of target food legumes, requiring urgent rice spikelets to >35°C for 5 days at anthesis induced
implementation of agronomic and genetic means of complete sterility (Satake and Yoshida 1978). As most
addressingthisthreat.PredictionsintheFourthAssessment legumes are indeterminate, the effect of a short period of
Report of the Intergovernmental Panel on Climate Change supra-optimaltemperaturesislesscertainandunlikelytobe
(Christensen et al. 2007) suggest that the warming trend as drastic as in determinate cereals. However, among
observed throughout much of the world over the past four legumes, high temperatures around flowering decreased
decadeswillcontinuethroughthetwenty-firstcentury,with flower number and seed set in peanuts (Prasad et al. 2000,
extreme events becoming more frequent. In addition, 2001, 2003; Kakani et al. 2002), kidney bean or common
rainfall will decrease in the mid-latitudes where most food bean (Gross and Kigel 1994; Prasad et al. 2002), and
Innovationsinagronomyforfoodlegumes 49
cowpea (Hall 1992). In 21 peanut genotypes, the optimum percent of conservation agriculture was practiced in the
temperature for pollen germination varied from 25.5°C to Americas and Australia, and <2% in the major food-
35.0°C and for pollen tube growth from 30.5°C to 36.8°C producingzoneoftheIndo-GangeticPlain(Derpsch2005),
(Kakani et al. 2002). Challinor et al. (2007) used a where major soil degradation processes have long been
modelingapproach to show that high temperatures reduced documented (Abrol et al. 2000). Implementation of conser-
peanut yields in some locations in India. vation agriculture has depended upon the development of
Agronomic options for combating increasing temper- appropriate no-till or minimum tillage implements and
atures and incidence of drought induced by climate change effective control of weeds, primarily through use of
are planting density, the use of fertilizers, fallows and herbicides (Baker et al. 2006).
rotations, time of planting, and supplemental irrigation to Major advantages of conservation agriculture are pur-
increase yields. Decreasing planting density is a widely ported to be reduced wind and water erosion of topsoil,
used procedure to mitigate the effects of low rainfall, increased water use efficiency through improved water
particularlywhenthecropisgrownonstoredsoilmoisture. infiltration and retention, increased nutrient use efficiency
The influence of changing planting density was simulated through enhanced nutrient cycling and fertilizer placement
in pigeonpea; increasing density counterbalanced yield adjacenttoseed, reduced oscillation of surface soil temper-
reductions when temperatures increased by 3°C, but only atures, increased soil organic matter and diverse soil
in years with high rainfall (Turner 2008). Moreover, biology, reduced fuel, labor and overall crop establishment
doubling the planting density left the same amount of costs, and more timely operations (Hobbs et al. 2008).
water in the profile at maturity, suggesting that changing However,the supposed benefitsof conservation agriculture
theplantingdensity didnotchange wateruseand therefore are not universal and Giller et al. (2009) pointed out
provides only limited scope to manage legume crops to circumstances where it did not appear to be advantageous,
overcome yield limitations induced by climate change. particularly for smallholder, resource-poor farmers. Such
Cooper et al. (2009) also showed that increasing nutrient farmers find it difficult to maintain a soil cover of crop
input in low input smallholder farming systems increased residue or a cover crop due to the competing requirements
yieldsmarkedlyandovercameanyyieldreductionsinyears for such biomass for fodder, fuel, or building material.
with higher temperatures from climate change. While the Appropriate herbicides are usually not available to, or
model was based on fertilizer input, the use of mixed affordable by, resource-poor farmers, resulting in increased
species legume fallows (Ndufa et al. 2009) to increase soil weeding costs and weed constraints if tillage is reduced
organic matter and nutrient status, and rotations to control under conservation agriculture. Minimum tillage/no-till
weeds and diseases, would help overcome yield reductions implements have mostly been developed for large tractor-
from climate change. The increasing variability of rainfall drawn equipment in extensive agriculture and are therefore
suggests that water conservation measures will become not available for smallholders reliant on draft power from
increasingly important. Prevention of runoff, minimum animals or small machines (e.g., two-wheel power tillers).
tillage to reduce soil evaporation, micro-catchments to Nevertheless, conservation farming in southern Africa that
concentrate water in the root zone, early planting to reduce incorporates basins to minimize runoff and greater water
soil evaporation before crop emergence, weed control and, infiltration, mulching to reduce water loss by soil evapora-
where available, use of strategically timed supplemental tion, timely planting on the first rains, application of
irrigation are all possible avenues for adapting to climate manure to provide better soil structure, top dressing with
change and are further discussed below. fertilizer depending on rainfall, rotation with legumes, and
timely weed control, have increased yields by up to 100%
and increased profitability over conventional farming
4 Role of legumes in conservation agriculture (Mazvimavi et al. 2008).
Legumes are ideal crops for two components of
Conservation agriculture is increasingly being practiced in conservation agriculture—soil cover and rotation—either
many parts of the world, mainly in response to increased as a growing crop or as residue. The benefits of food
recognition of soil degradation and thus sustainability of legumes in cereal-based cropping systems have been
agriculture. Conservation agriculture is defined as minimal discussed in detail by Siddique et al. (2008) and are
soil disturbance and permanent soil cover combined with summarizedasfollows. Themajoradvantageoflegumesis
rotations (Hobbs et al. 2008). Derpsch (2005) estimated the addition of fixed nitrogen (N) to the soil and non-
that, by 2005, 95.5 million ha would be farmed using depletionofexistingsoilNreservesbecauseoftheirability
principles of conservation agriculture, although not always to meet their own N needs through fixation. Legumes
simultaneously including all facets of the practice—mini- contributehighqualityorganicmattertothesoilbecauseof
mum tillage, ground cover, and crop rotation. Ninety-six their high N to carbon (C) ratio and are effective in
50 Siddiqueetal.
breakingdiseasecyclesofparticularcerealcropsbecauseof ducted by resource-poor farmers should favor increased
their genetic dissimilarity with cereals and thus host cultivation of target food legumes and hasten ingress of
differentsetsofpestsanddiseases.Manylegumesaredeep agronomic innovations that would increase their yield. First
rooted, contributing to nutrient cycling and water infiltra- attemptstointroduceconservationagriculture,andespecially
tion in the soil. Further, some legumes access nutrients minimum tillage, in all locations where it was eventually
otherwise unavailable to other crops, by mechanisms such widely adopted, met with initial skepticism from farmers,
as dissolution by root exudates, and render those nutrients researchers, extension agents, and input suppliers (Derpsch
available to subsequent crops. 2002). This is also the case for traditional smallholder
Soybean is a major component of conservation agricul- farming systems, but prospects for overcoming the over-
ture systems in the Americas, both contributing to and whelming constraints to conservation agriculture introduc-
benefiting from conservation agriculture practices. For tion in those circumstances are now becoming apparent.
example, soybean is a major component of conservation A first step is the introduction of minimum or zero
agriculture systems in Brazil, where there has been tillage(alsocalledconservationtillage)inagriculturewhere
widespread adoption of this practice over the previous full tillage, usually with animal traction, has been a
three decades (Bolliger et al. 2006). There are Brazilian tradition. Lack of access to minimum tillage implements
examples of conservation agriculture resulting in continu- developed for large-scale agriculture is considered a major
ous soil cover (minimizing erosion), gradual increases in constraint. However, in developing countries where four-
soil organic matter, integration of livestock, movement of wheeled tractors are used, simplified, low-cost versions of
surface-applied lime through the acid soil profile, breakage minimum tillage have been developed and adopted. An
of compact soil layers, and reduced reliance on agro- exampleisintheIndo-GangeticPlainofIndiaandPakistan
chemicals, all under a variety of climatic and edaphic where the area sown to no-till wheat has increased from
conditions, farm sizes, and degree of mechanization 12,800 ha in 1999–2000 to 2.4 million ha in 2005–2006
(Bolliger et al. 2006). The current target food legumes— (Hobbs et al. 2008). This increase did not rely on imported
lentil, chickpea, pea, and faba bean—are part of conserva- equipment from areas already practicing conservation
tion agriculture systems in North America, Australia, and agriculture but, based on concepts used in those areas,
Turkey,buttheirperformanceinthosesystemshasnotbeen local development and commercial manufacture of imple-
assessed to the extent of soybean. In Australia, some ments best suited to prevailing tractor types, soil types,
advantages of minimum tillage for pulses have been farming systems, and economic circumstances of the
quantifiedforwater-limitedenvironments.Intheseenviron- farming community. A major pre-requisite to widespread
ments, stubble retention in no-till systems (<20% soil adoption was low-cost and local manufacturing, repair, and
disturbance) significantly increases soil water storage servicing capability. This process is currently being trialed
(O’Leary and Conner 2007) and reduces soil compaction for chickpea, lentil, and other crops in northern Iraq and
(Li et al. 2001) as compared with tilled soil. Combinations Syria where, based on low-cost Indian designs, minimum
of wider row spacing (e.g., 30 vs. 20 cm) and stubble tillage planters are now being locally manufactured and
retention are proving advantageous for chickpea and lentil increasingly used (Piggin 2009).
by reducing herbicide damage and by the stubble acting In areas where four-wheel tractors are not so widely
as a trellis thereby improving harvestability and grain available,but two-wheel power tillers are widespread, such
quality (Crowe and Brand 2010). Adjustment of row as in Bangladesh and Nepal, prospects for converting to
spacing to match soil water availability has been an minimum tillage have recently risen. An evolutionary
important agronomic adaptation for maximizing pulses process has begun, from using power tillers for complete
yield in conservation agriculture systems in Australia rotarytillage,throughtomountingseedboxesontherotary
(Hawthorne 2010). tiller (power-tiller-operated seeder), to the reduction or
Whilethethreecomponentsofconservationagriculture— elimination of rotary tillage with delivery of seed and
minimum tillage, soil cover, and rotation—have effectively fertilizer behind tines (Hossain et al. 2009; Haque et al.
been combined in some systems in the Americas and 2010). There are two options for the latter; strip tillage,
Australia, it has been difficultto combine all componentsin whichleavesonlyonesetofrotorbladesdirectlyinfrontof
cropping systems including target legumes in developing each tine delivering seed and fertilizer, or zero tillage by
agriculture. Despite the general spread of conservation completely eliminating rotary tillage. Due to the limited
agriculture in Brazil,smallholder farmers are usually ableto tractionofpowertillers(usually12or16hp),zerotillageis
onlypartiallyadopttherecommendedtechnologiesduetothe only feasible on lighter textured soils, but strip tillage is
complex socioeconomic circumstances and resource limita- effective on heavier soils as the rotor blades not only make
tions they face (Bolliger et al. 2006). Introduction of thefurrowforthefollowingtinebutalsoassisttractionand
conservation agriculture into smallholder agriculture con- provide a micro-catchment for water infiltration. There are
Innovationsinagronomyforfoodlegumes 51
A change to conservation tillage (minimum or zero
tillage), along with adequate weed management, should
alone be attractive to smallholder farmers due to reduced
costs of land preparation and the many advantages of more
precise placement of seed and fertilizer. However, this
would provide an opening for the other two main pillars of
conservation agriculture—ground cover and crop rotation.
Thereducedrequirementfordraftanimalsreducestheneed
for crop residue as fodder, releasing residue for use as a
ground cover, with legume residue being of greater value.
The advantages of including legumes in the rotation,
especially in cereal–cereal rotations, would then become
more apparent. With increasing demand from farmers for
legume components in their cropping patterns, it would
become easier to introduce technologies required for their
Fig. 2 Versatile multi-crop planter (VMP), with seed and fertilizer yield maximization.
delivery attachments fitted to a Chinese-made two-wheel tractor
(power tiller), sowing lentil by strip tillage after rice, Bangladesh,
November2009.Themachinecanbeeasilymodifiedtosowbyzero
tillage (all rotary blades removed), full tillage (all rotary blades 5 Increasing water and nutrient use efficiency
present),andtosowonbeds
Recent research has indicated scope for increasing water
units available that are readily interchangeable between use efficiency (WUE) and nutrient use efficiency (NUE) in
traditional full rotary tillage, power-tiller-operated seeder, food legumes through agronomic means. WUE is defined
strip tillage, and zero tillage (Fig. 2; Enamul Haque, as grain yield per unit of water use, evapotranspiration, or
CIMMYT,Bangladesh,personalcommunication).Thestrip growing-season rainfall. In temperate and Mediterranean-
and zero-tillage options have been developed since 2005 type cropping systems, where legumes are grown on
during an Australian Centre for International Agricultural current rainfall, incoming rainfall can be lost as runoff,
Research project on promoting chickpea and lentil in deep drainage and soil evaporation or used by the crop in
northwesternBangladesh.Thestripandzero-tillageseeders transpiration. The combined loss of water by soil evapora-
were initially developedtohandlechickpeaand lentil seed, tion and transpiration is crop evapotranspiration. In sub-
but to be commercially viable they need to be able to sow tropical environments where cool-season legumes are
seed of most crops grown in the region. With adjustments generally grown on stored soil moisture from monsoonal
to seed metering devices and delivery mechanisms, this or summer rains, soil evaporation is generally a smaller
requirement has been met, even to the extent of handling fraction of total evapotranspiration because the soil surface
primed (pre-soaked) seed (Haque et al. 2010). is frequently dry. In general, increased WUE is associated
Foregoing complete tillage in smallholder systems will, with increased yield and water use after flowering (Loss et
in most soils, require alternative methods of weed manage- al. 1997; Siddique et al. 1998, 2001). In short-season
ment. Hand weeding alone will not suffice as the increased Mediterranean-typeenvironments,specieswithearlyflower-
weedingrequirementnegatesthereducedlaborrequirement ing,podding,andseedsethavehigheryieldsandWUEthan
and input costs offered by conservation agriculture. This thosewithlaterflowering,podding,andseedset(Siddiqueet
would suggest the requirement for herbicides, but this al. 2001). When the yields and water use of chickpea and
remains problematic particularly for resource-poor small- lentilwerecomparedover12growing seasonsatTelHadya
holder farmers. There are on-going problems of timely in Syria, the WUE for grain varied from 1.9 to 5.5 (mean
availabilityandaffordabilityofeffectiveproducts,andtheir 3.2) kg ha−1 mm−1 in chickpea and from 2.1 to 5.2 (mean
controlled use to prevent development of herbicide resis- 3.8) kg ha−1 mm−1 in lentil depending on growing season.
tance and toxicities to non-target organisms. For weed Differences among genotypes in transpiration efficiency
control in organic agriculture systems, where tillage is not (grain yield or above-ground biomass per unit crop
excluded, Bàrberi (2002) stressed the need to develop transpiration) have been demonstrated in a number of
system-oriented weed management systems. This involves legumes—peanut (Hubick et al. 1986), lentil (Matus et al.
a holistic understanding of crop/weed ecology and using 1996;Turneretal.2007),andchickpea(Turneretal.2007),
rotations, cover crops, sowing time/procedure, use of but not in narrow-leafed lupin (Turner et al. 2007). Such
competitive crop genotypes, planting pattern, and fertilizer differences are being used in cereal breeding programs in
strategy to minimize weed competition. Australia (Richards 2006). However, agronomic practices
52 Siddiqueetal.
have yielded greater increases in WUE (Turner 2004; by11%from4.2to4.7kgha−1mm−1(lateNovember)and
Turner and Asseng 2005). One way of increasing WUE in from 4.7 to 5.2 kg ha−1 mm−1 (late February), but did not
water-limited Mediterranean-type environments is by earli- increase the WUE of chickpea of 5.1 kg ha−1 mm−1 when
er planting. In faba bean grown at two sites in Western sown in mid-January (Oweis et al. 2004). While supple-
Australiaover2years,theWUEforgraindecreasedfrom6 mental irrigation is not always available, where it is
to 10 kg ha−1 mm−1 from early- to mid-May plantings available, it is a means of significantly increasing grain
down to 2–3 kg ha−1 mm−1 when planted in late June to legume yields and WUE.
early July, that is a decrease from 0.9% to 1.4% per day Well-grown food legumes can be self-sufficient in their
basedonmeasuredwateruse(Lossetal.1997).Siddiqueet N needs and contribute to the N economy of the entire
al.(1998)showedthatforeachday’sdelayinplantingafter cropping system by contributing fixed N to the soil pool
25 May, lentil yields decreased and WUE for grain and drawing little or none from soil reserves of N (Walley
decreased by 1.3% to 1.6% per day in 2 years when et al. 2007). However, to reach their growth and N-fixing
growing-season rainfall was about 300 mm. While water potential in most agro-ecosystems, they usually require
use decreased with later planting, grain yield decreased effective rhizobial inoculation (Clayton et al. 2004; Gan et
moreleadingtoreducedWUE.Thus,earlyplantingisakey al. 2005) coupled with supplemental inputs of elements
to higher yields and WUE in most years and crops. such as phosphorus (P), sulfur (S), boron (B), and
However, in field pea, planting too early increases the risk molybdenum (Mo). Over the last half century, the major
of black spot disease and reduced yields, and when lentil paradigm in alleviating nutrient deficiencies in field crops
was sown before 25 May in Western Australia, WUE has been the application of inorganic fertilizers to soil. In
decreased (Siddique et al. 1998). Possibly one reason why the case of non-legume crops in commercial farming, large
very early planting reduces WUE is that WUE is also amounts of N fertilizer in particular have been applied to
affected by the vapor pressure deficit of the air which permit crops to reach their yield potential. Ironically, the
decreases in autumn and winter and increases again in relatively cheap cost of N fertilizer, derived from oil and
spring in the Mediterranean and sub-tropical climates in natural gas during a period in which those commodities
whichcool-seasonlegumesaregrown.Asdiscussedabove, were at their cheapest, has discouraged cultivation of
conservation agriculture with herbicide use at sowing has legumes as the residual benefits offixed N have seemingly
enabledearlierplantingasweedsarenolongerremovedby become less important. Further, in attempts to maximize
cultivation prior to sowing. yields within a cropping season, excess and untimely
Herbicide use or hand weeding increases WUE by applications have been made, leading to nutrient losses
reducing the competition for water and nutrients below from the cropping system, through runoff, erosion, leach-
ground, and by reducing the competition for light above ing, and volatilization. Therefore, NUE, defined as eco-
ground, thereby increasing yields. The development of nomic yield per unit of nutrient applied, has declined over
herbicides to remove grasses and broad-leaved weeds in time. Further, nutrients lost from the agricultural system
legume crops in recent years has had a major influence on have often had detrimental effects on adjacent ecosystems,
WUE.Theimportantprogressinchemicalandnon-chemical especiallynaturalones(Cloernetal.2007).Therehasbeen
weedcontrolinfoodlegumesisdiscussedinthenextsection. a focus on maintaining the adequacy of the available,
The use of micro-catchments or basins to concentrate solublenutrientpooltomeetcropgrowthnutrientneeds,to
rainfall around roots and contour farming to prevent runoff the relative neglect and detriment of supplying power of
has increased WUE by providing more water for transpi- other pools, such as organic and soil mineral-bound pools.
ration rather than rainfall being lost as runoff or soil Thisapproachhasbeenfavoredbylowrelativecoststodateof
evaporation. Oweis and Taimeh (1996) found that the solublefertilizersbearingmajornutrientsandtherelativeease
overall efficiency of small water-harvesting catchments of chemical quantification of soluble pools (soil tests)
(water used by the crop as a proportion of the rainfall compared with other soil nutrient pools. This paradigm is
received) varied from 85% to 7% depending on the size of also largely being followed in developing countries, jeopar-
the catchment, root zone capacity, and crop water use dizing sustainability of agricultural lands, upon which large
(Oweis2005).Studieswithchickpeaandlentilhaveshown proportionsofthepopulationcontinuetodirectlyrely.
thatsupplementalirrigationcansignificantlyincreaseyields As a consequence of decreasing NUE, environmental
and WUE (Zhang et al. 2000; Oweis et al. 2004). In both damage, likely increased relative costs of inorganic fertil-
chickpea and lentil, yields increased linearly with the izers,andnutrientimbalancesarisingfromthepredominant
amountofwater applied, butWUEinchickpeavariedwith inorganic fertilizer paradigm, alternative strategies for
time of planting. With sowing in late November and late nutrient management of cropping systems are emerging.
February in northern Syria, supplemental irrigation of These have implications for nutrient supplementation of
80mmonaverageover4yearsincreasedWUEofchickpea food legumes and the role of legumes in sustaining
Innovationsinagronomyforfoodlegumes 53
cropping systems at higher levels of NUE while maintain- use of inorganic fertilizer is not precluded in their analysis.
ing,andevenincreasing,theproductivity ofthose systems. Figure3conceptuallysummarizesthedifferencesinflowsof
One such strategy is the ecosystem-based approach pro- N and P among the soil–plant pools under conventional
posedbyDrinkwaterandSnapp(2007).Theyarguethatthe cropping systems and the proposed ecosystem-based model.
focus on replenishing available nutrient pools with soluble The main features of their strategy are:
fertilizers has uncoupled N, P, and C cycles, exacerbated
nutrient losses from the system, and created a “fertilizer & strategic use of a variety of nutrient resources, rather
treadmill” due to diminution of microbial-based nutrient than an overwhelming focus on the soluble nutrient
cycling. Their proposed ecosystem-based approach tends pool and trying to replenish it with soluble inorganic
towards the principles of organic farming, emphasizing fertilizer application,
nutrientpoolsotherthantheimmediatelyavailablepool,but & active management of N and P soil pools,
Fig. 3 Qualitative representation
ConventionalAgriculture
ofN(greenarrows)andP(blue
arrows;blue-greenstriped=N+P) Gaseous losses
dynamicsinconventional
croppingsystems(above)and
ecosystem-orientedcropping N & P soluble
Plant & animal residues
systems(below).Arrowthickness fertilizer
Crop
representsrelativeproportionof
nutrientflow.AfterDrinkwater
andSnapp(2007)
Soil organic matter Mineralization Soluble inorganic N & P
& microorganisms
Pfixation
Mineral P reservoirs Solubilization
Leaching &
run-off
Erosion
Ecosystem-basedApproach
Gaseous losses
Plant & animal residues,
Crop N & P soluble
rock phosphate
fertilizer
Mineralization
Soil organic matter Soluble inorganic N & P
& microorganisms Assimilation
Pfixation
Solubilization
Mineral P reservoirs Leaching &
run-off
Erosion