Effect of Graded Saturation of Phosphorus Fixing Capacity of Soil on Yield and Yield Attributes of Maize (Zea mays)

A pot experiment was conducted during the summer season,2015 to study the effect of graded saturation of phosphorus fixing capacity of soil on yield of maize. Application of P equivalent to 100% P fixing capacity of the soil in addition to recommended dose of fertilizer (RDF) significantly increased the dry matter yield (48.33, 78.33, 65.00 g pot-1) and yield attributes i.e. plant height (122.66, 131.44, 133.89 cm) and fresh yield (185.33, 319.67, 226.67 g pot-1) of maize over the control in all the three different soils (loamy sand, clay loam and clayey). The significant highest nitrogen, phosphorus, potassium and sulphur content and uptake by plants were obtained through saturating the 100% phosphorus fixing capacity of the soil in addition to RDF in all the three different soils. Likewise, highest productivity of maize was obtained from clay loam textured soil. Highlights m Maize positively response to the higher saturation of phosphorus irrespective of soil types. m Saturation of the 100 percent phosphorus fixing capacity of soils in addition to recommended dose of fertilizer promotes growth, productivity and nutrient uptake in maize. m Clay loam soil is superior in terms of productivity over the clayey and loamy sand soils of Gujarat.

The phosphorus is an essential nutrient both as a part of several key plant structure compounds and as a catalyst in the conversion of numerous key biochemical reactions in plants. The origin of P deficiencies in these soils is threefold (Brady and Weil 1999). First, the total P level of the soils is low, ranging from 0.01 to 0.1% (Chen and Ma 2001). Second, the P compounds commonly found in these soils are highly insoluble. Third, when soluble sources of P, including those in fertilizers and manures, are added to soils they are sorbed to the soil, changed into unavailable forms and, over time, incorporated into highly insoluble compounds. The soil characteristics that influence P fixation include the amount and type of clay-fraction minerals, soil pH, soil organic matter content, soil temperature, time of reaction, exchangeable Al 3+ , soil redox condition (Sanchez and Uehara 1980), and root exudates. These factors are interactive rather than additive, which makes it difficult to predict inorganic P fixation under a wide range of soil conditions. Therefore, this study was undertaken using maize as a test crop at pot experiment at Anand, Gujarat.

MATERIALS AND METHODS
A pot experiment was carried out at net house during the summer season. Before starting the experiment in pots, soils from three locations were analyzed to estimate the phosphorus fixing

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Print ISSN : 1974ISSN : -1712 Online ISSN : 2230-732X capacity of the soils in laboratory condition as per the procedure outlined by Waugh and Fitts (1966).
The experiment was laid out in a completely randomized design with factorial concept, comprising fifteen treatment combinations of five levels of phosphorus (F 1 : only recommended dose of fertilizer (RDF) (N:P 2 O 5 :K 2 O -120:60:00 kg ha -1 ), F 2 : RDF + 50% saturation of P fixing capacity of soil, F 3 : RDF + 75% saturation of P fixing capacity of soil, F 4 : RDF + 100% saturation of P fixing capacity of soil and F 5 : RDF + 100% saturation of P fixing capacity of soil + 5 mg Zn kg -1 + 10 mg Fe kg -1 ) and three types of soil (S 1 : loamy sand, S 2 : clay loam and S 3 : clayey soil) which were replicated three times. Ten kilograms of soil was taken in earthen pots and initially six healthy seeds of maize were sown into each pot at proper depth and finally three plants were maintained for 60 days. Pots were watered regularly and weed free condition was maintained till 60 days after sowing (DAS) required for tasseling stage of maize crop. Then treatment-wise calculated quantities of fertilizers were applied in solution form (N through urea, phosphorus through KH 2 PO 4 , Zn through ZnSO 4 and Fe through FeSO 4 ) with irrigation water. Top dressing of 50% nitrogen through urea was done at 30 days after sowing (DAS).
Experimental data generated during the pot experiment were analyzed statistically for their test of significance as per Completely Randomized Design (factorial), at 5% level of significance Panse and Sukhatme (1978). After the analysis of most of the parameters, interaction effect of S X F was calculated. Then modified anova was prepared wherever applicable.
The initial physico-chemical properties of soils were as follows:

Plant height
The highest mean plant height (129.00, 138.67, 137.44 cm) was recorded in treatment RDF + 100% saturation of P fixing capacity of soil + 5 mg Zn kg -1 + 10 mg Fe kg -1 (F 5 ). The plant height was not significantly increased among the treatments as well as types of soil. Increase in plant height with the increase in phosphorus levels was recorded in all the three soil types but the difference in plant heights were statistically non significant (Table 1.). Plants grown in the clay loam textured soil gave significantly highest plant heights (128.76 cm).

Fresh yield
All the treatments differed from the only recommended dose of fertilizer (RDF) in respect of fresh yield of maize during the experimentation ( Table 1). Saturation of phosphorus fixing capacity of soil increased the fresh yield of maize in all the soils. This increase was found statistically non significant in the loamy sand and clayey soil but under clay loam soil it gave significant difference (Table 1.). Significantly highest fresh yield was noted under the treatment RDF + 100% saturation of P fixing capacity of soil + 5 mg Zn kg -1 + 10 mg Fe kg -1 (F 5 ). Treatments RDF + 50% saturation of P fixing capacity of soil (F 2 ), RDF + 75% saturation of P fixing capacity of soil (F 3 ), RDF + 100% saturation of P fixing capacity of soil (F 4 ) and RDF + 100% saturation of P fixing capacity of soil + 5 mg Zn kg -1 + 10 mg Fe kg -1 (F 5 ) produced 19.01%, 24.22%, 35.07% and 40.56% higher yield respectively over the RDF (191.44 g pot -1 ). These result corroborated with the earlier findings of Hussein (2009) in corn and Dhar et al. (1977) in berseem. Among the different three soil types significantly highest fresh yield (292.93g pot -1 ) of maize was obtained from the clay loam textured soil. The response of iron and zinc was not significant in all the three soils as the soils contain sufficient amount of iron (Fe) and zinc (Zn).
Increase in fresh yield of maize under different saturation treatments of phosphorus might be attributed to better availability of uptake of phosphorus and crop growth as against recommended dose of fertilizer (RDF)
The response of iron and zinc was not significant in all the three soils as the soils contained sufficient amount of iron (Fe) and zinc (Zn). The application of phosphorus equivalent to 100 per cent phosphorus fixing capacity of a soil in addition to RDF is the best treatment in S 2 (clay loam) and S 3 (clayey) while 75% saturation was sufficient to increase the yield significantly in S 1 (loamy sand). Significantly highest dry matter yield of maize was recorded from the plants grown in the clay loam textured soil (70.67 g pot -1 ) as compared to the rest two soils.

N, P, K and S content and uptake
Nitrogen, phosphorus, potassium and sulphur contents in plants and uptake by plants were significantly increased with the increase in phosphorus levels. Significantly higher nutrient contents (Table 2.) and uptake (Table 3.) were recorded under the treatment F 4 where 100 per cent phosphorus fixing capacity of soil was saturated with the additional dose of phosphorus in addition to RDF. Addition of Fe and Zn failed to give significant effect in nutrient contents and uptakes over the RDF + 100% saturation of P fixing capacity of soil (F 4 ). The results corroborate with the findings of Malik et al. (2014), Ijgude and Kadam (2008), Nagar andMeena (2004) andTeotiaet al. (2000). As compared to RDF, each level of saturation of phosphorus fixing capacity of soil was found superior. Nutrients content and uptake were found highest in the clay loam textured soil.

Interaction effects of S × F
Interaction effects of S × F remained statistically non significant for all the above parameters.

CONCLUSION
The results indicated that maize could positively respond to the higher saturation of phosphorus irrespective of soil types. Higher plant heights, fresh and dry matter yield, nutrient content in plants and nutrients uptakes in plants were achieved through saturating the 100 percent phosphorus fixing capacity of soils in addition to recommended dose of fertilizers (RDF) irrespective of soil types. Clay loam soil was found superior in terms of productivity over the clayey and loamy sand soils.