Decision Support Systems in Agriculture: Some Successes and a Bright Future - Efficient Decision Support Systems: Practice and Challenges from Current to Future - page 311

6.4.4 Successes
The integrated software was comprised of existing modules of PDSS and ADSS, both
modified to merge into the integrated framework called NuMaSS (Nutrient Management
Support System). A nitrogen module was added by North Carolina State University based
on the Stanford (1973) approach of determining a balance of what the crop needed relative
to the soil content with amendments and fertilizers added. The actual implementation,
while based on the Stanford approach, grew out of a dissertation of one of the project
members (Osmond, 1991). The NuMaSS software was disseminated in countries in West
Africa, Central and South America and in S.E. Asia (Thailand and the Philippines).
One of the notable initial successes of NuMaSS was that by following the diagnosis of soil
acidity conditions and following with the proper soil amendments, desired crops such as
mung bean ( Vigna radiata, L.) could be grown where the crop had died previously due to
the high soil acidity (Aragon et al., 2002). The decision-aid also indicated that other crops
could be grown and would require substantially less expensive limestone than did mung
bean. The initial success continued and gradually attitudes and awareness towards soil
acidity changed and producers became aware of the importance and limits in productivity
it caused. Several assessments of farmer attitude indicated substantial change in
awareness and prioritization of soil acidity (Aragon et al., 2002). An impact analysis at the
conclusion of the project reported that during the next 40 years the project results were
conservatively estimated to return about 45 million $US in benefits to the producers
(Walker et al., 2009).
Some other spectacular results occurred on the island of Negros Occidental where farmers
and producers had not been applying limestone and were basically unaware of soil acidity.
In this province maize yields of over 7 metric tons were obtained with the addition of
nutrients according to NuMaSS predictions. This contrasted to yields of maize of 1 to 2 tons
without the addition of nutrients or limestone (D. Cidro, 2006 personal communication).
The impact of the introduction of NuMaSS and introducing specific management of the acid,
uplands soils seems on track to expand and extend well beyond the province of Isabela
where the Walker et al. (2009) study took place. Other provinces of Northeastern Luzon
have begun instituting province-wide programs of applying limestone. This contrasts to the
total lack of commercial agricultural limestone in the regional city of Ilagan when the project
begun. It was not clear that the rapid and extensive adoption of the liming technology was
due to NuMaSS, but it seems likely that the dissemination was enhanced by the presence of
the decision-aid.
6.4.5 Disadvantages
While it is clear that the NuMaSS software assisted and improved food crop yields in the
Philippines, it was also clear that there were problems with the nitrogen component,
especially in Thailand and Laos. A dissertation study was carried out comparing N
recommendations from two decision-aids (NuMaSS and DSSAT (Jones, 1998)). The results
indicated that neither software adequately estimated the minimum amounts of fertilizer N
that should be applied. A dissertation study indicated that there was substantial residual
nitrate that should be measured and which reduced the fertilizer nitrogen requirement
(Sipaseuth et al., 2007).
Unfortunately, the results of the multiple expert work described in the Propa system (see
section 6.2) had not yet become available and separate, non-interacting systems for nitrogen,