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Ammonium nitrate (34%), fused phosphate (17%), and muriate of potash (52%) were applied as inorganic sources of N, P, and K. Recommended doses of the chemical fertilizers N, P (P2O5), and K (K2O) were 80 : 50 : 40 kg ha−1, and this amount was divided into three equal portions. The first part was applied as a basal dose and the two remaining portions were given during the vegetation period. All other agronomic operations such as plant protection, weeding, and irrigation measures were conducted similarly in all plots.
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That's not a control group or anything. That's just saying the soil also had that in it along with the manure. Here it is in context:
The seedlings of chilli pepper were transplanted into a plastic greenhouse, rain-shelter plastic house, and open field at the experimental station located in Unbong-eup, Namwon-si, Jeollabuk-do, Republic of Korea. The experiment was set in randomized complete block design with three replicated plots (15 m × 4 m) for each treatment.
The chemical analyses of organic manure were conducted to estimate N, P2O5, and K2O contents before application. The organic manure consisted of 67.06% organic matter, 2.42% N, 1.51% P2O5, and 0.41% K2O. Two different levels of organic matter were applied to each temperature treatments as per experimental layout. Based on a soil analysis, 132.7 kg ha−1 (1×) of livestock manure compost as an optimum and 265.4 kg ha−1 (2×) was applied as the double rate of organic manure.
Ammonium nitrate (34%), fused phosphate (17%), and muriate of potash (52%) were applied as inorganic sources of N, P, and K. Recommended doses of the chemical fertilizers N, P (P2O5), and K (K2O) were 80 : 50 : 40 kg ha−1, and this amount was divided into three equal portions. The first part was applied as a basal dose and the two remaining portions were given during the vegetation period. All other agronomic operations such as plant protection, weeding, and irrigation measures were conducted similarly in all plots.
No mention of a control group, or of a different mix that had organic only, or anything like that.... unless I'm missing it.
It even says in the paper:
Our goal in this study was to evaluate the effect of 1× rate (132.7 kg ha−1) and 2× rate (265.4 kg ha−1) livestock manure treatments compared to control (without manure) on the growth and yield parameters of chilli peppers grown under three different environmental conditions such as a plastic greenhouse, rain-shelter plastic house, and open field conditions.
The control is.... without the manure....