**2. Materials and methods**

Amongst ways of soil fertilization, increasing use and continuous application of inorganic fertilizers seemed to be limited because fertilizers in Africa are 2 – 6 times more expensive than that of in Europe, North America, and Asia [1]. Applying plant residue or organic bio‐ mass to soil has influenced on soil nutrients, soil physical condition, soil biological activity, and crop performance. However, applying these organic fertilizing materials such as rice straw and husk, green manure or organic biomass (*i.e.* leaf biomass) to soil are not attractive to farmers compared to straw burning due to short term effects of organic materials on crop yield are often small. Cutting and carrying biomass to the field also require high labor and cost. On other hands, crop residues have high economic value and have been used as live‐ stock feed and fuel so leaving crop residues in the field is seldom. Even though, incorpora‐ tion of rice straw which is abundant and widely spread in the rice field can return and reserve most of nutrients to soil particularly N, P, K, S, and Si in long term [5]. Tobita et al. [6] and Issaka et al. [3] reported that adding rice straw to rice system could gain approxi‐ mately 20 percent of N and P, and most K relative to the needs of applied chemical fertiliz‐

ers in the Northern region of Ghana where rice cultivation is the most prominent.

leustalf soil in Nigeria.

226 Soil Fertility

Crop management such as tree fallow system is not attractive for farmer because they prefer better land use alternative owing to population pressure particularly in the humid and trop‐ ical regions. Besides, improved fallows have not been proved yet on their benefits in semiar‐ id tropics of Africa. The potential of fallow system on shallow and poorly drained soil is poor [1]. Growing leguminous plants as fallows before cropping season or intercropping with crop is effective crop management to accumulate N for consecutive crops. However, it should be noted that effects of plant residues on soils and crops depend on the quality (*i.e.* carbon/nitrogen ratio, lignin, and polyphenol contents) and the decomposition rates of resi‐ dues which in turn control the nutrient release rates. Tian et al. [7] found that the contribu‐ tion of low quality plant residues as mulching on maize grain yield and protein concentration was lowest in comparison to intermediate or high quality residues on Oxic Pa‐

Animal manures from poultry, pig, cow, goat, and sheep contain all the major nutrients. These manures are very good materials for improving soil fertility and crop productivity [8,3]. Tobita et al. [6] reported that if only 20 percent of total livestock organic resource esti‐ mated in Ghana was utilized, so it could replace the requirement for chemical fertilizer in rice cultivation system entire the Northern region. However, gathering bulky dung of live‐ stocks or excreta (dung and urine) from grazing livestock was difficult particularly in rural area where these manures are not sold and scarce [9]. Unlikely, poultry manure may be val‐ id in urban center where intensive production of poultry has being implemented. In present, poultry manure is on high demand but its quantity is not enough for farmer's need resulting

farmers have to pay in advance before manure will be delivered to the field [3,10].

Many soils in sub-humid and humid tropics including SSA have very low levels of natural P, thus P fertilization is essential for maintaining desired level of crop yield. Buresh et al. [2] indicates that input of P fertilizers is required to replenish P stock in highly P deficient soils

**1.3. Alternative P fertilizer utilizing methods**

This work gathered information from published papers (secondary data) focusing on the utilization of small quantity of fertilizer to boost crop productivity in wide-range of cli‐ mates and soil conditions. The effective methods have been revealed including 1) fertilizer microdose application, 2) addition of small amount of fertilizer to the seed by coating, 3) increase of nutrient concentration in seedling by soaking in, or dipping seedling in the nu‐ trient slurry. Moreover, two experiments were conducted to investigate the effects of fertil‐ izer seed coating and fertilizer seedling soaking on the early growth of rice (*Oryza sativa* cv. IR74) grown on acidic P deficit soil.

#### **2.1. Fertilizer seed coating method**

Treatments were triplicated and comprised of 1) control\_uncoated; 2) control\_oil; 3) Burki‐ na Faso phosphate rock (BPR); 4) Potassium dihydrogenphosphate (KH2PO4) and 5) NPK (14-14-14). The 15 seeds of IR74 rice were coated by 2 levels of ground fertilizer (18 or 36 mg) using vegetable oil as adhesive material. By this method, ground fertilizers were mixed with seeds at approximately 1.2 and 2.4 mg per seed. Coated seeds were sowing di‐ rectly into moistened soil. Soil used in this experiment was collected from Tropical Agri‐ culture Research Front (TARF). Massive amount of soil was collected, air dried, and sieved to 2 mm. Five hundred gram of air dry soil was weighed into bag. Soil properties were pHH2O, 4.83; EC, 6.03 mS m-1, and Bray 1-P, 1.66 mg kg-1. The basal nutrients were mixed to each soil (mg kg-1 soil); Na2MoO4.2H2O; 0.36; H3BO3, 0.71; CuSO4.5H2O, 5; ZnSO4.7H2O, 10; MnSO4.H2O, 15; MgSO4.7H2O, 21; CaCl2.2H2O, 71; K2SO4, 142; NH4NO3, 200, respectively. Percentage of plant emergence was monitored at 5, 10, and 15 day after sowing (DAS), and then thinned to 4 seedlings. Watering was done daily. Plant height, tiller number, and leaf age were measured at 20 and 40 DAS. Two rice plants were sam‐ pled for shoots and roots from each treatment at 20 and 40 DAS, oven-dried to obtain dry matter, and ground prior to further chemical analysis. Total P in plant organs was deter‐ mined after dry-ashing procedure.

**3. Results and discussion**

Fertilizer microdosing or known as microdose fertilizer application or point application is an application method of small, affordable quantity of fertilizer with the seed at planting time or as top dressing 3-4 weeks after emergence [15]. This application method has been developed by the International Crops Research Institute for the Semi-Arid Tropics (ICRI‐ SAT) and its partners to improve inorganic fertilizer use of farmers in Sahel region, Africa. This method is documented to enhance fertilizer use efficiency, high probability of yield re‐ sponse, crop productivity with favorable fertilizer per grain price ratio rather than spread‐

Alternative Fertilizer Utilizing Methods for Sustaining Low Input Agriculture

http://dx.doi.org/10.5772/53578

229

Microdosing soil with fertilizer uses about one-twentieth of the amount of fertilizer used on corn, and one-tenth of the amount used on wheat in America. Particularly, this pity amount often doubles crop yields on African soils due to they are starved of macronutrients such as N, P, and K. Small doses of fertilizers, about a full bottle cap or a three-finger pinch per a hole of planting are required and this amount equals to 6 gram of fertilizer or about 67 pound of fertilizer for every 2.5 acres or 30 kg fertilizer per hectare. Farmers just prepare small holes before the rain starts when soils are still hard. Later, fertilizers and seeds shall be put in the hole when the rain begins and the soils provide enough moist condition, encour‐

Successful works have been showed through Tabo et al. [17] who reported the yields of sor‐ ghum and millet were increased from 44 to 120% after adoption of fertilizer microdosing in harsh semi-arid climate of Mali, Burkina Faso, and Niger, the western Africa where soils were sandy and low in fertility with 500-800 mm annual rainfall. Farmers, themselves, se‐ lected plant varieties and types of fertilizer which were differed among countries and availa‐ bility of fertilizer on the local markets. Rates of fertilizer micro-dose per hill of planting were 4 g of NPK (15-25-15) in Burkina Faso, 4 g of NPK (17-17-17) in Mali, and 6 g of NPK

Bagayoko et al. [16] compared the effectiveness of fertilizer microdosing among no fertilizer microdosing check (farmer's practice), blank (zero fertilizer application), microdosing only, microdosing plus 20 kg P2O5 ha-1 and 30 kg N ha-1 in wide range of climates and soils in Bur‐ kina Faso, Mali, and Niger. It was found that microdose fertilizer application increased yields of grain and stover of pearl millet across wide range of climates and soils in Burkina Faso, Mali, and Niger. Additional supply of 20 kg P2O5 ha-1 and 30 kg N ha-1 had much in‐ creased grain and stover yields of pearl millet. Fertilizer microdose rates were 4 g of NPK (15-15-15) or equivalent to 62.5 kg ha-1 in Burkina Faso, 2 g of DAP (18-46-0) or equivalent to 33.2 kg ha-1 in Mali, and 4 g of NPK (15-15-15) or equivalent to 62.5 kg ha-1 in Niger. Nutrient

Hayashi et al. [18] demonstrated that millet farmers could delay inorganic fertilizer applica‐ tion or timing of using the micro-dosing technology from 10 to 60 days after sowing without the reduction of profits and their economic returns relative to the non-fertilizer applied

ing fertilizer over the field, root systems, and soil water capture [15,16].

(15-15-15), 2 g DAP (18-46-0), and 2 g DAP + 1 g Urea (46-0-0) in Niger.

sources of N as urea (46-0-0) and P as 0-46-0 were additionally supplied.

**3.1. Fertilizer microdosing**

aging root growth [15].

#### **2.2. Fertilizer seedling soaking**

Treatments were triplicated and comprised of 1) control (+P soil); added P soil [adding Ca(H2PO4)2; 331.4 mg] with non-fertilizer soaked rice (conventional method by farmers); 2) control (-P soil); non P added soil with non-fertilizer soaked rice, and other treatments were conducted on non added P soil with soaked rice by 3) Potassium dihydrogenphosphate (KH2PO4) solution; 4) NPK (14-14-14) solution. Five seedlings of 6-7 leaf age rice were soaked in 1 % and 5% (w/v) of each fertilizer solution with 2 soaking periods (30 min or 60 min). Freshly soaked seedlings were transplanted directly into flooded soil. Rice seedlings were thinned to 3 seedlings at 7 days after transplanting (DAT). Rice seedlings used in this experiment were grown on fully fertilized soil for 3 weeks before soaking and transplanting into pots. Three kilogram of 2 mm sieved soil was weighed into 1/5,000 are-pot. The basal nutrients were mixed to soil at the same rate of previous experiment described above. Water was added daily to maintain submerged/flooded condition. Tiller number and leaf age were monitored at 20 and 40 DAT. Plant height was measured at 20, 40, and 75 DAT, and then a rice plant was harvested for shoot and root at 20 and 40, and 75 DAT, then oven-dried to obtain dry matter, and ground prior to further analysis for total P concentration after dry ashing procedure.

#### **2.3. Data and statistical analysis**

The JMP 9.0.0 (SAS Institute Inc., USA) was used to perform ANOVA and compare the means by the Tukey Kramer HSD for plant growth (height, tiller number, leaf age), shoot and root DM, P concentration, P uptake.
