Geel, W.C.A., van

Haan, J.J., de

Smit, A.L.

Zwart, K.B.

English

Wageningen Yield 

CAN INTENSIVE ARABLE FARMING SYSTEMS ON 
SANDY SOILS IN THE NETHERLANDS MEET THE 
TARGETS IN THE NITRATE DIRECTIVE? 
J.J. de Haan1, K.B. Zwart2, A.L. Smit3, W.C.A. van Geel1  
 
 
1
 Applied Plant Research, Wageningen UR, The Netherlands, janjo.dehaan@wur.nl 
2
 Alterra, Wageningen UR, The Netherlands, kor.zwart@wur.nl  
3
 Plant Research International, Wageningen UR, The Netherlands, bert.smit@wur.nl  
 
 
Introduction 
Arable and horticultural farms on sandy soils in the South East of the Netherlands are until 
now unable to meet the EU-target of 50 mg nitrate per litre in groundwater. In the last 20 
years nitrate levels have decreased from 180-200 mg nitrate per litre to 70-100 mg per litre. 
However, little progress has been made in recent years (Hooijboer et al., 2007). In the project 
Nutrients Waterproof, an integrated and an organic farming system with arable and 
horticultural crops have been developed and tested between 2005 and 2008 in order to 
comply with these water quality targets. In these farming systems different measures are 
combined to reduce nitrate leaching (Haan et al., 2006).   
 
Materials and Methods 
The integrated system contained the crops potato, triticale, lilies, peas, leek, maize and sugar 
beet in a six year rotation. The integrated system consisted of two parts. In one part only 
chemical fertilizers were used whereas in the other part a combination of organic manure and 
chemical fertilizer were applied. The organic system contained the crops potato, alfalfa, leek, 
broccoli, maize, spring barley and tree nursery crops. In the organic system, only organic 
manure was used and no chemical crop protection was used. In both the integrated and 
organic systems, all practically available measures with positive effect on nitrate leaching 
were applied. Examples of these measures are: an efficient fertilization strategy based on crop 
uptake, taking into account uptake efficiencies, available mineral nitrogen (from soil, 
preceding green manure crops, crop residues and fertilization). Further, efficient fertilization 
techniques such as row fertilization (in maize and leek), split fertilization strategies (based on 
soil mineral N and crop reflection measurements) as well as the use of catch crops were 
applied where possible.  
The systems were developed in 2004 and tested between 2005 and 2008. All operations and 
inputs were registered; yield and N-content was assessed of both the crop and the crop 
residues. Mineral nitrogen contents in the soil were measured before and after a crop and 
before the start of the leaching season. During the leaching season every three weeks nitrate 
concentrations in ground water and surface water were measured.  
 
Results 
An overview of the results is presented in Table 1. Nitrate concentrations in groundwater in 
the organic system (41 mg NO3- l-1) met the targets of the nitrate directive due to extensive 
use of cover crops and leguminous crops. Nitrate concentrations in the integrated system 
were more than twice the target concentration when organic manure was used (116 mg NO3- 
l-1). The rotation of the integrated system contains more vulnerable crops and hardly any 
green manure crops because most crops are harvested late in the season. Total nitrogen input 
of the systems was about equal however available nitrogen for crop growth was higher in the 
integrated systems. Besides, mineral nitrogen in the organic system comes gradually 
available by mineralization during the growing season. Fertilization levels in the integrated 
system were conform to current legal limits, indicating that lower levels would have negative 
effects on yield levels (data not shown). Fertilization levels in the organic system were about 
half the legal limits. 
Nitrate concentrations of groundwater in the integrated system decreased with 25 mg l-1 to 91 
mg NO3- l-1 where no organic manure was used. However, after two years crop yields seems 
to decline as well. In 2007, crop yields were on average 5.4% lower in the integrated system 
with chemical fertilizer only; in 2008 2.4% lower.  
Crop yields in the integrated system with manure were on average comparable to average 
yields in the region and on average about 10% less than the crop yields aimed at in the 
region. Yield levels aimed at in the organic system are lower than in the integrated system.  
Only 57-59% of the available mineral nitrogen during crop growth is taken up by the main 
crops. This means that a large quantity of mineral nitrogen is available for leaching. However 
partly this is taken up by catch crops, especially in the Organic system.  
 
Tab. 1. Average results of the cropping systems 2005-2007. 
 
Cropping system Nitrate 
concentration 
groundwater  
mg NO3- l-1 
Crop yield / 
Regional 
good crop 
yield  
Total N 
input chem. 
& org. fert. 
kg ha-1 
Available 
mineral N for 
crop growth1  
kg ha-1 
N uptake / 
Available 
mineral N 
Integrated system 
chem. and org. fert. 
116 100.0% 294 305 57% 
Integrated system 
chem. fertilizer only 
91 97.5% 255 294 57% 
Organic system 41 95.5% 298 231 59% 
1
 including mineralization and deposition 
 
Discussion 
The integrated system did not comply with the water quality targets. The organic system did, 
mainly because of a more extensive crop rotation and larger possibilities for cover crops. In 
general the ratio between N uptake and available mineral N is low. Improvement of N-
efficiency is difficult without changes in rotation. Innovative technical measures are needed 
to reduce nitrate leaching in the integrated systems as extensification of conventional 
agriculture is not seen as an option because of loss of income and employment. These 
measures are currently in development. First example is the development of new catch crops 
which establish better after late sowing and do not propagate plant parasitic nematodes. A 
second example is the removal of nitrogen rich crop residues from e.g. broccoli, leek or sugar 
beet. When harvested around 1 November, 20-60% of the 100-150 kg nitrogen from the crop 
residues of leek and broccoli was leached. For sugar beet this was only 5-15% (Ruijter, 
2008). When harvested more early in autumn the losses are supposed to be higher. Another 
solution for horticultural crops is the use of drip irrigation and fertigation. Yields and nutrient 
uptake may be somewhat higher at comparable fertilization levels. However costs are higher 
as well. The question is however, if these measures are sufficient to lower nitrate leaching 
sufficiently. Therefore new research is started about cropping outdoor horticultural crops out 
of the soil in recirculating hydroponic systems. Nitrogen leaching can be controlled much 
better and yield levels and labour circumstances are expected to be much better, although 
profitability of these systems is doubted. (Haan et al., 2009).  
 
References 
Hooijboer, A.E.J. et al. 2007. Waterkwaliteit op landbouwbedrijven. Evaluatie Meststoffenwet 2007. RIVM 
rapport 680130002/2007 (in Dutch). 
Haan, J.J. de, et al. 2006. Stringent post harvest measures on sandy soils are needed to meet water quality 
targets. In: Schröder, J.J. & J.J. Neeteson. N management in agro ecosystems in relation to the Water 
Framework Directive. Proc. 14th N-workshop. Plant Research International. Wageningen. p. 77-79. 
Haan, J.J. de, et al. 2009. Design of New Vegetable Production Systems in the Netherlands. ISHS-bulletin. In 
press. 
Ruijter, F. 2008. Nitraatuitspoeling uit gewasresten van broccoli, prei en suikerbiet. BO-05-infoblad-23, 
Cluster BO-05 Mineralen en Milieukwaliteit. Wageningen UR. Wageningen (in Dutch). 


Nitraatuitspoeling uit gewasresten van broccoli, prei en suikerbiet.

Stringent post harvest measures on sandy soils are needed to meet water quality targets.

Waterkwaliteit op landbouwbedrijven. Evaluatie Meststoffenwet

Can intensive arable farming systems on sandy soils in the Netherlands meet the targets in the nitrate directive?

de Haan, J.J.

van Geel, W.C.A.

NARCIS 

Name not available

Can intensive arable farming systems on sandy soils in the Netherlands meet the targets in the nitrate directive?

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