Management of inorganic fertilizer is very important to obtain maximum crop yield and improved nutrient use efficiency in cereal crops. Fixation of phosphatic fertilizers in alkaline soils due to calcareousness is one of the major hurdles. It induces phosphorus nutritional stress that can decrease the yield of maize and wheat. Selection of a suitable application method and proper stage of crop for phosphorus (P) fertilizer has prime importance in better uptake of P and crop production. Among different application methods, soil and foliar application are widely adopted. In wheat and maize, knee height + tasseling and stem elongation + booting are critical stages towards P deficiency. That is why field trials were conducted to evaluate the supplemental effect of foliar P on maize and wheat yields. For that, 144 mM KH₂PO₄ was applied as foliar at knee height + tasseling and stem elongation + boot stages in maize and wheat, respectively. Soil application of 0, 20, 40 and 60 kg P ha⁻¹ was done through broadcast and band methods. Results showed that foliar spray of 144 mM KH₂PO₄ at knee height + tasseling and stem elongation + boot stages in wheat and maize significantly enhanced grains yield and phosphorus use efficiency (PUE) where P was applied as banding or broadcast at the time of sowing. A significant decreasing trend in response to increasing soil P levels validated the efficacious role and suitability of foliar P. In conclusion, the use of P as foliar at knee height + tasseling and stem elongation + boot stages is an efficacious way to manage P fertilizer.

In calcareous soils, wheat productivity is much lower due to improper nutrient management, especially phosphorus (P). Therefore, this study was conducted to manage P availability from various organic (Control, FYM and Sugar cane straw applied at the rate of 10 ton ha⁻¹) and inorganic (Control, 100% rock phosphate (RP), 50% acidulated RP, 100% acidulated RP, single super phosphate (SSP) and diammonium phosphate (DAP)) sources applied at the rate of 90 kg P₂O₅ ha⁻¹ in calcareous soil while using wheat as test crop. When averaged across the organic sources, SSP performed better in emergence m⁻² (126), tillers m⁻² (431), spikes m⁻² (419), grains spikes⁻¹ (61), plant height (95.1 cm), 1000-GW (40 g), biological yield (11,023 kg ha⁻¹), grain yield (4022 kg ha⁻¹), phosphorus use efficiency (10.5%), phosphorus in leaves at tillering (2.63 mg kg⁻¹) and anthesis stage (2.50 mg kg⁻¹), soil P at heading (1.73 mg kg⁻¹) and post-harvest stage (1.56 mg kg⁻¹) compared to the rest of the mineral sources. Similarly, among the organic sources, FYM performed better than others for all tested traits. Integration of inorganic P sources with organic manures further improved crop performance and post-harvest soil P content. Therefore, using 10 tons FYM ha⁻¹ in integration to SSP or 100% acidulated RP at the rate of 90 kg P₂O₅ ha⁻¹ is recommended for ensuring optimum wheat productivity under calcareous soils.

A research study was established at the research farm of the University of Agriculture, Peshawar during winter 2018–2019. Commercial biochars were given to the experimental site from 2014 to summer 2018 and received 0.95, 130 and 60 tons ha⁻¹ of biochar by various treatments viz., (Biochar₁) BC₁, (Biochar₂) BC₂, (Biochar₃) BC₃ and (Biochar₄) BC₄, respectively. This piece of work was conducted within the same study to find the long-term influence of biochar on the fertility of the soil, fixation of N₂, as well as the yie1d of chickpea under a mung–chickpea cropping system. A split plot arrangement was carried out by RCBD (Randomized Complete Block Design) to evaluate the study. Twenty-five kilograms of N ha⁻¹ were given as a starter dosage to every plot. Phosphorous and potassium were applied at two levels (half (45:30 kg ha⁻¹) and full (90:60 kg ha⁻¹) recommended doses) to each of the four biochar treatments. The chickpea crop parameters measured were the numbers and masses of the nodules, N₂ fixation and grain yield. Soil parameters recorded were Soil Organic Matter (SOM), total N and mineral N. The aforementioned soil parameters were recorded after harvesting. The results showed that nodulation in chickpea, grain yield and nutrient uptake were significantly enhanced by phosphorous and potassium mineral fertilizers. The application of biochar 95 tons ha⁻¹ significantly enhanced number of nodules i-e (122), however statistically similar response in terms of nodules number was also noted with treatment of 130 tons ha⁻¹. The results further revealed a significant difference in terms of organic matter (OM) (%) between the half and full mineral fertilizer treatments. With the application of 130 tons ha⁻¹ of biochar, the OM enhanced from 1.67% in the control treatment, to 2.59%. However, total and mineral nitrogen were not statistically enhanced by the mineral fertilizer treatment. With regard to biochar treatments, total and mineral N enhanced when compared with the control treatment. The highest total N of 0.082% and mineral nitrogen of 73 mg kg⁻¹ in the soil were recorded at 130 tons ha⁻¹ of biochar, while the lowest total N (0.049%) and mineral nitrogen (54 mg kg⁻¹) in the soil were recorded in the control treatment. The collaborative influence of mineral fertilizers and biochars was found to be generally non-significant for most of the soil and plant parameters. It could be concluded that the aforementioned parameters were greater for treatments receiving biochar at 95 tons or more per hectare over the last several years, and that the combination of lower doses of mineral fertilizers further improved the performance of biochar.

A field study was conducted on the reuse of wastewater from Mardan city to evaluate its risk of contaminating soil and wheat grains at different NPK levels. Three irrigation sources i.e. waste water (WW), canal water (CW) and alternate waste + canal water (WW+CW) were applied to wheat (cv Atta Habib 2010) grown at 0, 50, 75 and 100% NPK levels of 120:90:60 kg N:P₂O₅:K₂O ha^-1 at Palatoo Research Farm, Amir Muhammad Khan Campus, Mardan during 2015.The results showed higher grain and biomass yields in WW irrigated plots as compared to CW at NPK levels up to 50% of recommending dose revealing supplementing nutrient requirements in deficient conditions. However, irrigation of WW at higher NPK levels especially at or beyond 75% of recommended dose tended to reduce the crop yield that could be associated with heavy metals toxicity and nutritional imbalances. The use of WW substantially increased AB-DTPA extractable Zn, Mn, Pb, Ni and Cd indicating a potential threat to soil contamination. Similarly, WW irrigated wheat had higher concentrations of these heavy metals as compared to CW which limits its use for production purposes without any remediation measures. The alternate use of CW and WW as revealed by its comparative lower contamination in soil and wheat than sole WW could be one of the possible solutions and may increase the time required for threshold soil contamination.

This study compared the accuracy of various soil phosphorus assessment methods to measure the soil's ability to supply plants with phosphorus over a brief period in the field. Twenty individual soil samples were collected from a standing wheat (Triticum aestivum L) crop at depths ranging from zero to twenty centimeters. An equivalent plant spike sample was also procured from the soil sampling fields. In comparison to the wet acid digestion method used to detect phosphorus in plants, several methods were utilized to assess phosphorus in the soil, including resin extractable phosphorus, AB-DTPA extractable phosphorus, NaHCO3 extractable phosphorus, water-soluble phosphorus in suspension, and paste. The levels of variation and deficiency of phosphorus, which were found by different methods followed different patterns as shown by the fact that, AB-DTPA method finds phosphorus deficiency in 20% of samples while on the other hand, Olsen method finds phosphorus deficiency in 80% of samples. Even with such a small sampling area, none of the procedures showed a significant correlation with any other method that might account for uneven variation among the samples when determined by distinct procedures. However, corrections were observed to a certain degree between ammonium bicarbonate-diethylenetriaminepentaacetic acid (AB-DTPA) extractable and resin, as well as between other procedures and the plant P scale. Both resin and ammonium bicarbonate-diethylenetriaminepentaacetic acid (AB-DTPA) had a strong relationship with plant phosphorus, with the former showing a significant correlation of 0.48 and 0.21, respectively. Hence Resin and AB-DTPA methods are recommended for the determination of phosphorus under certain soil and plant conditions.