Increasing concern is focused on the environmentalimpact of horti-
cultural production that is characterized by a high input of fertilizers,
pesticides, and in some cases heavy machinery. It is obvious and has
been demonstrated excessively that consistently high and economical
yields are very difficult to achieve if the input of these factors is re-
duced. Hence, the overlap between yield and environment, area “1” in
Figure 15.1, is to be considered as a problem area that must be covered
by research.
Including qualityinto the target system complicates matters even
more. This is due to the fact that all three targets are interdependent
when one considers the production and handling procedures that are cur-
rently used to achieve these goals. Factor input to achieve high internal
and external quality of the product, area “2” in Figure 15.1, is a key area
of future research, whereas we feel that that optimization of yield and
quality without consideration or even at the expense of the environment,
area “3” in Figure 15.1, will lose importance.
The challenge for the future research is area “4” in Figure 15.1: in-
tegrating the production goals yield, environment, and quality. In this
field we have the least information at the moment, and research is com-
plex, timely and expensive. This fact calls for new approaches.
One example of how the competing goals within the horticultural pro-
duction can be approached comprises the supply of mineral and organic
fertilizer to improve yield and quality but also to protect natural re-
sources and avoid losses to the environment. The application of nitro-
gen using organic and mineral fertilizers in agriculture is necessary to
balance the amounts removed by harvested produce and waste. The up-
take itself can be controlled within a wide range by the amount of fer-
tilizers applied.
Six long-term experiments, lasting 12–28 years and performed on
sandy and loamy soils were analyzed for the balance of supplied, used
and lost quantities of nitrogen fertilizers (Rühlmann and Geyer, 1999).
The supplied nitrogen clearly increased the amount of nitrogen taken up
by the canopy (Figure 15.2). The effectiveness of mineral and organic
sources of nitrogen to increase the nitrogen uptake by the plants was dif-
ferent for the mineral and organic fertilizers; e.g., 55% of the applied
mineral nitrogen and only 15% of the applied organic nitrogen was used
by the plant. The remaining part was either used to build up organic ni-
trogen fractions in the soil or was lost either to the atmosphere or to the
groundwater. Strategies that avoided an average annual nitrogen supply
above 120 kg ha^1 led to average annual losses of less than 10 kg ha^1.
What are the Problems? 287