Cotton is a major cash crop of Pakistan that provides high foreign exchange and plays an important role in agriculture, industry, and economic development. The plant population is important in achieving high cotton yield and fiber quality attributes in irrigated conditions. Most farmers maintain plant spacing according to their local tradition, and often ignore the varietal characteristics in Pakistan that cause low yield and poor quality of products. Therefore, standardization of plant spacings according to varietal characteristics is important to achieve higher yield and fiber quality. A field experiment was carried out at the Agronomic Research Area, Muhammad Nawaz Shareef University of Agriculture, Multan, Pakistan in 2017, in order to evaluate the performance of four cotton cultivars (MNH-1016, FH-Lalazar, NIAB-878, and Cyto-124) under five plant spacings (15.0, 22.5, 30.0, 37.5, and 45.0 cm), comparing them with and without nitrogen application. Nitrogen fertilization was applied at the rate of 197 kg ha⁻¹. The experiment was replicated thrice, as per Randomized Complete Block Design with factorial arrangements. The results showed that nitrogen application of 197 kg ha⁻¹ showed a positive impact on all crop parameters compared to plots where no nitrogen fertilizer was applied. The wider plant spacing (45 cm) increased the values of many cotton parameters compared with other plant spacings (22.5, 30.0, 37.5 and 45.0 cm), but the seed cotton yield was found to be higher in the narrow plant spacing (15 cm). However, fiber quality parameters such as GOT, staple strength, and micronaire showed higher values under wider plant spacing (45.0 cm). The varieties showed a mixed effect on cotton productivity and fiber quality. The MNH-1016 significantly impacted yield-contributing parameters such as bolls plant⁻¹, boll weight and seed cotton yield. The NIAB-878 showed a higher photosynthetic rate and stomatal conductance compared to other varieties. Therefore, the wider plant spacing with nitrogen application could be a better strategy to increase cotton growth, yield, physiology, and fiber quality. However, long-term studies under different climatic conditions are suggested for wider plant spacing with nitrogen fertilizers.

Low nitrogen-use efficiency (NUE) is a serious issue for cotton production and environmental sustainability in arid climates. A pot study was conducted to evaluate the effect of K nutrition on NUE and performance of low- and high-K-efficiency cotton cultivars under two moisture regimes. Treatments included two soil moisture levels—i.e., normal irrigation, 100% available water content (AWC); reduced irrigation, 50% AWC—three levels of nitrogen (N)—i.e., 0, 375, and 750 mg N pot⁻¹—and two K levels, i.e., 0 and 208 mg K pot⁻¹. Results reveal that 208 mg K pot⁻¹ application with nitrogen significantly enhanced the N-use efficiency, growth, and yield attributes of both cotton cultivars compared with sole N fertilization. Similarly, the combined application of NK @ 375 N + 208 K mg pot⁻¹ caused up to 83% increase in NUE under AWC_50% and AWC_100%, as compared with NK control (0 N + 0 K). Compared with the control, imposed low-moisture stress caused a decrease of 13.9% in stomatal conductance (g_s), 2.5% in transpiration rate (E), and 6.5% in net photosynthetic rate (P_N), respectively_. The physiological water use efficiency (P_N/E) decreased by 13.2% under AWC_50%. Applied NK @ 375 N:208 K, mg pot⁻¹ caused 27.39 and 27.56% improvement in the P_N/E in HKE and LKE cultivars under AWC_50%, respectively. The HKE cultivar, i.e., CIM-554, maintained the highest g_s and P_N than FH-901, that was low-K-efficiency cultivar. The study suggests that varietal selection and adequate K fertilization have the prospects to improve NUE and save considerable quantities of fertilizer and irrigation water in cotton production under arid environments.

Despite the critical role of balanced nutrition in crop productivity, the use of potash (K) and zinc (Zn) is not much practiced by Pakistani farmers. The reduced nutrient uptake and crop productivity together increase the costs associated with fertilization and revisit farmers’ confidence in the efficacy and profitability of fertilizers. To address this problem, a field study was conducted in the research area of the MNS-University of Agriculture, Multan, in collaboration with Engro Fertilizers Limited. The research plan consisted of five treatments, including T₁ = control (without N, P, K, and Zn fertilizers), T₂ = NP in practice (NP at 32–23–0 kg acre^-1), T₃ = recommended NP (NP at 48–34.5 kg acre^-1), T₄ = balanced NPK (NP+K at 48–34.5–30 kg acre^-1), and T₅ = balanced NPK + Zn (NPK+Zn at 48–34.5–30 + 7.5 kg acre^-1). Wheat was used as a test crop, and its growth, yield, and physiological and nutritional parameters were studied. The results indicated that NPK+Zn balanced nutrition increased plant height, spike length, photosynthetic rate, water use efficiency, transpiration rate, stomatal conductance, and grain yield by 13%, 15%, 44%, 60%, 63%, 39%, and 78%, respectively, compared with the control. It was found that the combined application of NP, K, and Zn improved the recovery efficiency of applied nutrients, i.e., nitrogen recovery efficiency (NRE) by 230%, phosphorus recovery efficiency (PRE) by 136%, potassium recovery efficiency (KRE) by 135%, and zinc recovery efficiency (ZnRE) by 136% compared to NP-alone application. Agronomic use efficiency of applied fertilizers, such as potassium agronomic use efficiency (KAUE) by 71%, phosphorus agronomic use efficiency (PAUE) by 72%, nitrogen agronomic use efficiency (NAUE) by 70%, and zinc agronomic use efficiency (ZnAUE) by 72%, was observed compared to NP-alone application. The results showed that NPUE, PPUE, NPUE, and ZnPUE were reduced by 5%, 3%, 3%, and 5%, respectively, compared to NP-alone application. Our findings suggest that K and Zn should be made an essential part of wheat nutrition management for higher yield and better quality of produce.

Management of nutrients under changing climatic conditions has become a major challenge in agriculture, affecting nutrient availability, plant uptake, and overall crop productivity. Optimizing fertilization strategies, particularly through balanced fertilizer applications, is crucial to enhancing nutrient use efficiency and ensuring sustainable crop yields under these dynamic environmental conditions. This study contributes to improving nitrogen management strategies for wheat in calcareous soils by evaluating different nitrate and ammonium ratios, offering insights for enhancing nitrogen use efficiency and yield optimization. The treatments included: T₁ = DAP-Urea (100% N as NH₄⁺), T₂ = DAP-CAN (29% N as NH₄⁺ and 71% N as NO₃⁻), T₃ = NP-Urea (32% N as NH₄⁺ and 68% N as NO₃⁻), and T₄ = NP-CAN (100% N as NO₃⁻). Results showed that N uptake varied with NH₄⁺/NO₃⁻ ratios in the fertilizer combinations. Wheat supplied with 100% N as NO₃⁻ (NP-CAN) had higher N, P, and K use efficiencies compared to plants with 100% N as NH₄⁺ (DAP-Urea). Plants with 100% N as NO₃⁻ had higher INR, NACE, NARE, and NAUE (77%, 43%, 83%, 24 kg kg^− 1) compared to those with 100% N as NH₄⁺ (67%, 26%, 29%, 18 kg kg^− 1). FUTE decreased to 33% (NP-CAN) from 40% (DAP-Urea), while NPUE dropped to 29 g g^− 1 (NP-CAN) from 67 g g^− 1 (DAP-Urea). The fertilizer stress factor increased from 60% (DAP-Urea) to 67% (NP-CAN). Similar trends were observed in P and K use efficiency. Plants with higher agronomic parameters and grain yield per hectare also showed improvements in PUE and KUE. Economic analysis indicated that nitrate-based NP combinations generated 13–42% more net income and 3–12% higher BCR compared to DAP-Urea. The VCR (3.13 to 5.04) suggests that nitrate-based combinations are economically viable for farmers.

Phosphorus use efficiency in soils of Pakistan is reported less than 15%. However, phosphorus (P) bio-fertilizers have potential to improve P use efficiency (PUE) in these soils on sustainable basis. A primary study was conducted under control conditions of greenhouse to compare P availability from reduced rates of phosphorus bio-fertilizer (PSB-DAP) with P available from 100% rate of DAP recommended for maize. Based on the findings, a field study was conducted to evaluate the effects of 100% rate of uncoated DAP and 50-75% rate of PSB-DAP on corn yield and PUE. The treatment for both studies included; control (with fertilizers), 100% of recommended P2O5 from Commercial DAP (C-DAP100), 75% of recommended P2O5 from PSB-DAP (PSB-DAP75) and 50% of recommended P2O5 from PSB-DAP (PSB-DAP50). Results explored that available P from PSB-DAP50 and C-DAP100 was statistically at par while PSB-DAP75 at 30, 45 and 60 days of incubation. The findings of field study also revealed that PBS-DAP improved cob weight by 5-10%, chlorophyll contents by 14-23%, 1000-grains weight by 8-10%, grain yield by 10%, and P uptake by 35%, PUE efficiency by 42% compared to C-DAP100. This work can be used as a case study to promote P bio-fertilizers among farming community and researchers in order to for make effective use of alternate P sources for crop production.