adewale nafiu

In most developing countries including Nigeria, fertilizers are applied to the soil by uneducated farmers without particularly making reference to the specific need of the plant or soil. Therefore, intended efficiency/replenishment is not maximized and fertilizer use is not rationalized. This paper critically reviews the three basic approaches to soil fertility evaluation: Visual symptoms of nutrient deficiency, Plant tissue analysis and soil testing. The implications of these methods are examined in terms of predicting fertilizer requirements for crops in Nigeria. Furthermore, the paper discusses the methods of Soil fertility evaluation available. Focus is then shifted primarily to the soil testing method, describing in detail the main objectives behind carrying out soil testing, including the proper soil sampling tools, sound sampling techniques and handling of the samples.

The study was carried out during the wet cropping season of 2000 and dry season of 2001, respectively at the farm site of Olabisi Onabanjo University, Ago-iwoye, Ogun State in SouthWest zone of Nigeria to determine the weight of cane, dry matter and yield of four varieties of sugarcane (Saccharum officinarum L.) in response to NPK 20: 10: 10 fertilizer. Varieties of sugarcane used were Co62175, NCS005, NCS004 and NCS003 and the treatments were laid out in Randomized Complete Block Design (RCBD) replicated three times. The statistical analysis was done using Analysis of Variance (ANOVA) and means were separated with LSD (Least Significant Difference) at p < 0.05. Results showed significant differences between the varieties of the sugarcane with Original Research Article

Soil degradation and nutrient depletion have become serious threat to agricultural productivity in
Nigeria. Substantial improvement in the systems is required to support the ever-increasing rural
and urban population. During the 2013 and 2014 cropping season, field experiments were
conducted to evaluate the effect of combined application of NPK fertilizer and Biosoil conditioner on
yield and growth of maize at Kilankwa (longitude 6.79316E, latitude 8.70545N) in Abuja, Nigeria.
This experiment was done as a randomized complete block design with three replications. The
treatments were T1 (300 kgNPK/ha); T2 (300 kgNPK/ha + 1 tablet of Biosoil conditioner in 50 litres
of water); T3 (1 tablet of Biosoil conditioner in 50 litres of water) and T4 (control). Soil samples
were collected for the determination of chemical and physical properties before planting. Data ongrowth parameters (plant height and number of leaves) and yield (fresh cob weight) were also
collected and subjected to 2 ways Analyses of Variance (ANOVA) and means separated with Least
Significant Difference (LSD) at P=0.05.
The study revealed that during dry season of 2013 cropping system, application rate of 300 kg
NPK/ha + 1 tablet of Biosoil conditioner in 50 litres of water had the highest fresh cob weight (6.0
t/ha), followed by 300 Kg NPK/ha only (5.1 t/ha), 1 tablet of Biosoil conditioner only (3.2 t/ha) and
control (2.3 t/ha) respectively. The field evaluation also showed that combined application rate of
300 kgNPK/ha + 1 tablet of Biosoil conditioner in 50 litres of water /ha produced the highest
number of leaves (13) and plant height (251 cm) compared to the least value of 10 and 123 cm
respectively as obtained in the control.
Similarly in the 2014 wet season, the same trend as in the 2013 was obtained with the application
rate of 300 kg NPK/ha+1 tablet of Biosoil conditioner in 50 litres of water had the highest fresh cob
weight (10.9 t/ha), followed by 300 Kg NPK/ha only (9.0 t/ha), 1 tablet of Biosoil conditioner only
(7.4 t/ha) and control (3.0 t/ha) respectively.
It can be concluded that the combined application of 300 kgNPK/ha and 1 tablet of Biosoil
conditioner in 50 litres gave the highest values for growth and yield than the sole application of
either NPK or Biosoil conditioner.

Aside from increasing the yield of crops, it is well known that application of fertilizers, especially Nitrogen, to soil has many other positive and negative effects. One of such effects include increasing or decreasing disease expression and/or severity. Information about the effect of continuous application of Nitrogen fertilizers to important cereals such as maize, in areas where local farmers have low access to information and technology, might go a long way in helping stakeholders to manage diseases. Two commonly cultivated maize cultivars, DMRE–Y and DMR– LSR-W, were planted in a randomized complete block design, first in Abeokuta (early cropping season of year 2000) and then in Ago-lwoye (early cropping season of year 2001) to evaluate the effect of increasing rates of Nitrogen fertilizer (in form of urea) application on stalk rot disease 56 caused by Macrophomina phaseolina and root rot disease caused by Fusarium moniliforme. Increasing rate of Nitrogen application led to a significant increase in the severity of these diseases with the highest disease expression at 300 kg N ha-1. Although the reactions of the two cultivars were similar, DMRE-Y was found to be more susceptible to these rots than DMR-LSR-W. Simple linear regression analysis indicated a very strong positive relationship between N rates and average disease index. A two year pooled index for DMRE-Y cultivar gave correlation coefficient values 0.9997 and 0.9844 for stalk and root rots respectively while for DMR-LSR-W cultivars, the values were 0.9933 and 0.9815 for stalk and root rots respectively. Increasing rates of urea increased the grain yield but had diverse effects on yield components. The rates had no effect on plant height and ear length but considerably increased the kernel row and kernel weight. It, however, reduced days to 50% tasseling of maize crops.