There is no alternative to phosphorus (P) in agriculture as it is second most important plant nutrient after nitrogen. Mineral P fertilizers are derived from rock phosphate (RP) which is finite, non-renewable and geographically restricted to a few countries, thus its shortage likely affects agriculture in near future as the world population is growing at a greater pace. This could increase P inputs in agriculture in order to meet rising food demands which may result in the depletion of RP reserves. Furthermore, P losses from farmlands in case of mineral P fertilizers also demands the sustainable use of P not only because of its finite resources but also the environmental concerns associated with P fertilization such as eutrophication. The present study was designed to formulate biochar-based P fertilizer that would help in the sustainable use of P fertilizer. Biochar(s) were prepared using wheat straw at 350–400 °C pyrolytic temperature followed by enrichment with Di-ammonium phosphate (DAP) taking into account all possible combination of DAP to biochar on the w/w basis (0:100, 25:75, 50:50, 75:25 and 100:0). Enrichment was carried out using two different methods i.e., phosphorus enriched biochar (PEB1) by hot method and cold method (PEB2). An incubation experiment was performed to assess the impact of each biochar on selected properties of soil. The treatments were organized in factorial arrangement under complete randomized design (CRD) with three replications. Both the amendments were applied at rate of 1% of dry soil on a w/w basis. A significant increase in soil extractable P and total nitrogen (N) was recorded for the ratio 50:50 as compared to control as well of rest of treatments. Similarly, high organic contents were found for both PEB1 and PEB2 at the ratio 50:50. An incubation experiment was followed by pot trial using 50:50 for both PEB1 and PEB2 and split doses of recommended P were applied (0%, 25%, 50% and 100%) with a control under CRD with three replications using chickpea as test crop. Both PEB1 and PEB2 with 50% P have significantly improved crop growth, yield, nodulation, and plant physiological and chemical parameters as compared to a recommended dose of P alone. The result may imply that the integration of P-enriched biochar and chemical fertilizer could be an effective approach to improve chickpea production and soil properties.

Sustainable management of phosphorus (P) is one of the burning issues in agriculture because the reported P losses, when applied in the form of mineral fertilizer, give rise to another issue of water pollution as P is considered one of the limiting nutrients for eutrophication and so results in costly water treatments. In the present study, the enrichment of biochar with mineral P fertilizer was supposed to reduce such losses from the soil. Additionally, P can also be recycled through this technique at the same time as biochar is derived from biomass. Biochar was prepared using wheat straw followed by its enrichment with di-ammonium phosphate (DAP) at the ratio of 1:1 on a w/w basis. The first pot trial for spring maize (cv. Neelam) was conducted using phosphorus-enriched biochar (PEB) at 0% and 1% with different levels of recommended P (0%, 25%, 50%, and 100%). The treatments were arranged factorially under a complete randomized design (CRD) with three replications. After harvesting the spring maize, pots were kept undisturbed, and a second pot trial was conducted for autumn maize in the same pots to assess the residual impact of 1% PEB. In the second pot trial, only inorganic P was applied to respective treatments because the pots contained 1% PEB supplied to spring maize. The results revealed that the application of 1% PEB at P level 50% significantly increased all the recorded plant traits (growth, yield, and physiological and chemical parameters) and some selected properties of post-harvest soil (available P, organic matter, and EC) but not soil pH. In terms of yield, 1% PEB at 50% P significantly increased both the number of grains and 100-grain weight by around 30% and 21% in spring and autumn maize, respectively, as compared to 100% P without PEB. It is therefore recommended that P-enriched biochar should be used to reduce the inorganic P fertilizer inputs; however, its application under field conditions should be assessed in future research.

This study was planned to examine the effects of exogenous silicon supply on growth parameters and arsenic accumulation level in rice. The experiment was conducted in the wire house of Saline Agriculture Research Centre, Institute of Soil and Environmental Science, University of Agriculture Faisalabad. The study was comprised of treatments viz: control; (100 µM Arsenic); (200 µM Arsenic); (5 mM Silicon); (5 mM Silicon + 100 µM Arsenic) and (5 mM Silicon + 200 µM Arsenic). Results revealed that maximum shoot fresh weight, shoot dry weight, root fresh weight and root dry weight were observed in (5 mM Si) solution. In the same way, maximum number of tillers was also recorded in (5 mM Si) solution; while silicon application failed to alleviate arsenic concentration of rice genotype.