Plant Demand Adapted Fertilization in Organic and Precision …
155
worldwide, a meta-analysis of 107 datasets from 64 trials [30] showed that mineral
fertilizer application led to a 13% increase in organic carbon and 15% increase in the
microbial biomass (Cmic) above levels in unfertilized control. While N fertilization
tended to reduce Cmic in soils with a pH below 5 (−11%), it had a significantly
positive effect in soils of pH ranging from 5 to 7 (+8%) and pH 7 or higher (+48%).The
input of N per se does not seem to negatively affect Cmic in cropping systems. Singh
[86] reviewed the positive benefits of balanced fertilization on soil organic carbon
in various long-term experiments in India in various climatic zones. Benbi and Brar
[8] showed that intensive agriculture with fertilizers in Punjab in North India, led to
increase in soil organic carbon by 38% from 0.29 to 0.4% over a period of 25 years
(1981–2006). It can be expected that when nutrients are applied in precision mode
these differences will be even more and precision agriculture can also contribute to
improvement of soil health besides saving nutrients and reducing losses.
4 Integrated Nutrient Management
Conventional precision farming and organic farming approaches have been well
researched, contrasted and compared in many studies. In most situations in developing countries, balanced fertilization, integrated nutrient management (INM) and
integrated pest management are in use by farmers for long. Addition of organic
manures alone or in combination with fertilizers has been found in several studies to
increase the efficiency of soil, manure and fertilizer nutrients as compared to conventional application of fertilizers [77]. The basic principle of INM is to maintain or
adjust plant nutrient supply to achieve a given level of crop production by optimizing the benefits from various sources of plant nutrients like chemical fertilizers
and organic sources.
Three approaches were developed for optimizing organic and inorganic nutrient
doses.
Approach 1: Substitution of certain proportion of the generally recommended dose
of NPK (25–50% of GRD) through organic manures and biofertilizers. These doses
for different crops developed through model agronomic trials are used. Depending
upon the availability of quantity of organic manures, a certain proportion of GRD
particularly N is substituted through organic manures and biofertilizers. This is a
widely used approach of INM followed by the soil testing laboratories.
Approach 2: A soil test based NPK dose for different crops is computed by soil
test crop response correlation equations (STCR) using target yield, initial soil test
values, nutrient requirement of crops and use efficiency of soil and fertilizer nutrients. Depending upon the amount of organic manures available, a certain proportion
of this STCR based dose (25–50%) is substituted through organic manures and
biofertilizers.
155
worldwide, a meta-analysis of 107 datasets from 64 trials [30] showed that mineral
fertilizer application led to a 13% increase in organic carbon and 15% increase in the
microbial biomass (Cmic) above levels in unfertilized control. While N fertilization
tended to reduce Cmic in soils with a pH below 5 (−11%), it had a significantly
positive effect in soils of pH ranging from 5 to 7 (+8%) and pH 7 or higher (+48%).The
input of N per se does not seem to negatively affect Cmic in cropping systems. Singh
[86] reviewed the positive benefits of balanced fertilization on soil organic carbon
in various long-term experiments in India in various climatic zones. Benbi and Brar
[8] showed that intensive agriculture with fertilizers in Punjab in North India, led to
increase in soil organic carbon by 38% from 0.29 to 0.4% over a period of 25 years
(1981–2006). It can be expected that when nutrients are applied in precision mode
these differences will be even more and precision agriculture can also contribute to
improvement of soil health besides saving nutrients and reducing losses.
4 Integrated Nutrient Management
Conventional precision farming and organic farming approaches have been well
researched, contrasted and compared in many studies. In most situations in developing countries, balanced fertilization, integrated nutrient management (INM) and
integrated pest management are in use by farmers for long. Addition of organic
manures alone or in combination with fertilizers has been found in several studies to
increase the efficiency of soil, manure and fertilizer nutrients as compared to conventional application of fertilizers [77]. The basic principle of INM is to maintain or
adjust plant nutrient supply to achieve a given level of crop production by optimizing the benefits from various sources of plant nutrients like chemical fertilizers
and organic sources.
Three approaches were developed for optimizing organic and inorganic nutrient
doses.
Approach 1: Substitution of certain proportion of the generally recommended dose
of NPK (25–50% of GRD) through organic manures and biofertilizers. These doses
for different crops developed through model agronomic trials are used. Depending
upon the availability of quantity of organic manures, a certain proportion of GRD
particularly N is substituted through organic manures and biofertilizers. This is a
widely used approach of INM followed by the soil testing laboratories.
Approach 2: A soil test based NPK dose for different crops is computed by soil
test crop response correlation equations (STCR) using target yield, initial soil test
values, nutrient requirement of crops and use efficiency of soil and fertilizer nutrients. Depending upon the amount of organic manures available, a certain proportion
of this STCR based dose (25–50%) is substituted through organic manures and
biofertilizers.